History of Ghostscript versions 1.n

# History of Ghostscript versions 2.n

## Table of contents

> - Version 2.9.10-beta (7/28/94)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Streams, Library
> - Version 2.9.9-beta (6/23/94)
>   - Documentation, Platforms, Fonts, Interpreter, Library
> - Version 2.9.8 (6/20/94)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.9.7-beta (6/5/94)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.9.6-beta (5/23/94, not distributed to the public)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.9.5-beta (4/11/94)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Interpreter, Library
> - Version 2.9.4-beta (2/19/94)
>   - Procedures, Utilities, Drivers, Platforms, Interpreter, Library
> - Version 2.9.3-beta (1/19/94)
>   - Documentation, Procedures, Drivers, Platforms, Interpreter, Library
> - Version 2.9.2-beta (1/2/94)
>   - Documentation, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.9.1-beta (12/7/93)
>   - Utilities, Interpreter, Library
> - Version 2.9-beta (12/6/93)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Interpreter, Library
> - Version 2.8-beta (11/10/93)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.7.2-beta (10/11/93)
>   - Utilities, Interpreter, Library
> - Version 2.7.1-beta (10/4/93, not distributed to the public)
>   - Documentation, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.7-beta (9/20/93, not distributed to the public)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.6.1 (5/28/93)
>   - Documentation, Procedures, Utilities, Drivers, Platforms, Fonts, Interpreter, Library
> - Version 2.6 (5/9/93)
>   - Documentation, Procedures, Utilities, Platforms, Fonts, Drivers, Interpreter, Library
> - Version 2.5.2 (9/20/92)
>   - Procedures, Utilities, Platforms, Drivers, Interpreter, Library
> - Version 2.5.1 (9/11/92)
>   - Procedures, Utilities, Platforms, Fonts, Drivers, Interpreter, Library
> - Version 2.5 (8/18/92)
>   - Procedures, Utilities, Platforms, Fonts, Drivers, Interpreter, Library
> - Version 2.4.2 (5/8/92)
>   - Procedures, Utilities, Platforms, Fonts, Drivers, Interpreter, Library
> - Version 2.4.1 (4/21/92)
>   - Procedures, Utilities, Drivers, Fonts, Interpreter, Library
> - Version 2.4 (3/25/92)
>   - Procedures, Utilities, Drivers, Fonts, Interpreter, Library
> - Version 2.3 (8/28/91)
>   - Utilities, Drivers
> - Version 2.2 (6/1/91)
>   - Procedures, Drivers, Fonts, Utilities, Interpreter, Library
> - Version 2.1.1 (1/15/91)
>   - Build procedures, Interpreter, Drivers, Library
> - Version 2.1 (12/31/90)
>   - Build procedures, Drivers, Fonts, Interpreter, Library
> - Version 2.0 (9/12/90)
>   - Miscellaneous, Drivers, Build procedures, Interpreter, Library

This document is a history of Ghostscript releases numbered 2.n. For more recent changes, see the the other history documents and, for the latest versions, the new:

> News
> History of Ghostscript versions 4.n
> History of Ghostscript versions 3.n
> History of Ghostscript versions 2.n (this document)
> History of Ghostscript versions 1.n

For other information, see the Ghostscript overview.

## Version 2.9.10-beta (7/28/94)

This is the last 2.9 beta, since 3.0 will be released on July 31.

### Documentation

    Fixes bugs:
    	- A | in gs.1 had a \ in front of it instead of \\.

    Adds a paragraph in gs.1 that tells how to select paper size.

    Notes in devs.mak that the cdj550 driver is the best one for the H-P
    DeskJet 520, and the pjxl300 driver is the right one for the H-P DeskJet
    1200C.

    Notes in make.doc that Watcom C++ 10.0 may require a change in a makefile.

### Procedures

    Removes ICCINIT from MODULES.LIS for VMS systems.

    Updates VMS.MAK to support Motif V1.2.

    Updates jpeg.mak to work with version 5alpha4 of the IJG JPEG code.

### Utilities

    Fixes bugs:
    	- font2c didn't leave extra room in Type 0 font dictionaries for
    entries added by definefont.
    	- font2c left extra information on the stack.
    	- ansi2knr would remove newline characters within formal argument
    lists.
    	- font2c got an Error: /undefined in makefontprocname.

    Updates ansi2knr to work better with the GNU configure program.

    Updates ansi2knr to handle procedure formal arguments automatically.

### Drivers

    Fixes bugs:
    	- If a file contained color or gray-scale information followed by a
    masked image, the X driver would sometimes invert the polarity of the
    image.

### Platforms

    Fixes bugs:
    	- Unix systems with a 2-argument gettimeofday returned garbage
    values for the current time.
    	- The VMS build script for compiled fonts omitted the requirement
    to load gs_ccfnt.ps.
    	- memory_.h didn't note that System V Unix platforms need memmove.

    On Unix systems, changes the subdirectory of $datadir/ghostscript to just
    be the version number (e.g., 2.9.10 rather than gs-2.9.9).

### Fonts

    Adds support code for the Wadalab (University of Tokyo) free Kanji font.

    Notes in the documentation in Fontmap that .pfa and .pfb fonts are
    compatible with ATM, but .gsf fonts are not.

    Changes the names of Thomas Wolff's expanded Hershey fonts, replacing .gsf
    with .pfa.

### Interpreter

    Fixes bugs:
    	- The scanner became confused if the literal names /<< or />>
    straddled an input buffer boundary.
    	- .setlanguagelevel gave an invalidaccess error when
    switching from level 2 to level 1.
    	- currentgstate, setgstate, and copy for gstates didn't do
    the necessary access checks.
    	- The Category resource category didn't define .ResourceFile, so
    /Category resourcestatus gave an error.
    	- The garbage collector didn't trace the structures used by
    filenameforall properly on most platforms.
    	- Automatically expanding systemdict didn't work, but didn't give
    an error.
    	- Automatically expanding a dictionary usually expanded it by too
    much.
    	- systemdict was created too small.
    	- The garbage collector didn't trace the structures referenced only
    from allocator objects, leading to attempts to access freed storage.
    	- If a chunk was empty, the GC tried to free it even if it had
    inner chunks.
    *	- The outer loop in dict_find_name_by_index() could cause an
    addressing fault on segmented machines when looking up Level 2 operators,
    because the offset could get decremented past 0.
    	- The heap_available procedure in gsmemory.c didn't convert
    properly to non-ANSI syntax.  (New bug in 2.9.9.)
    	- The ledgertray procedure wasn't implemented.
    	- The xxxtray procedures didn't set the page size.
    	- The settumble operator wasn't implemented, even as a dummy.
    	- glyphshow didn't work with Type 3 fonts.
    	- Supplying a RenderTable for a CIE color space caused an error.
    	- The DCT filter code had the jpeg/ subdirectory name "wired in" to
    the source files.

    Adds experimental filters for Burrows/Wheeler block sorting compression
    (BWBlockSortEncode/Decode), described in DEC SRC Research Report #124,
    move-to-front coding (MoveToFrontEncode/Decode), and a simple form of
    Huffman coding (BoundedHuffmanEncode/Decode).  These are experimental -- do
    not rely on them remaining the same (or existing at all) in future
    releases!

    Adds all function prototypes needed to pacify strict compilers.

    Removes all explicit references to userdict from the C code.

    Changes the SAFER switch so that it disallows not only explicit writing,
    deleting, or renaming of files, but also disallows specifying an explicit
    OutputFile for any device (except for the initial device, by means of
    -sOutputFile= on the command line).

### Streams

    Fixes bugs:
    	- Hex decoding (ASCIIHexDecode stream and <> literals) didn't treat
    the data source as read-only (although it restored it to its original
    contents).

    Implements move-to-front coding, a simple form of Huffman coding, and
    Burrows/Wheeler block sorting compression.

### Library

    Fixes bugs:
    *	- (The following bug fix was actually implemented somewhere around
    version 2.7.)  restore didn't purge character cache entries whose keys were
    names created more recently than the save.
    	- gstype1.h declared gs_type1_state_sizeof as an extern, but this
    wasn't defined anywhere.
    	- gs_makeimagedevice didn't set the size of the palette correctly,
    which confused the GC.
    	- gs_makeimagedevice didn't set num_components to 1 for
    mapped-color devices with only gray values.
    *	- The two-color halftoning algorithms truncated when computing the
    halftone level, rather than rounding it.
    *	- If a path being filled had line segments that fell entirely to
    the right of the clipping region, part of the path might not be filled.
    	- The optimized code for 24-bit color didn't ensure properly that
    32-bit accesses would be aligned appropriately.
    	- The miter join check had gotten reversed somewhere along the way.
    *	- Because x and y were interchanged in the miter check computation,
    in some situations the check was inverted.  (This is a very old bug!)
    	- It was believed that strokepath didn't work with dashed lines;
    the problem appears to have been an incorrect testing program.

    Adds all function prototypes needed to pacify strict compilers.

    Changes fixed2float so it doesn't cast the result to float, and removes
    fixed2double.  This produces slightly more accurate results in many places,
    and may even be faster (for FPUs that normally generate double rather than
    single precision results).

## Version 2.9.9-beta (6/23/94)

### Documentation

    Puts a pointer to devs.mak in the section of use.doc that talks about
    MS-DOS displays.

### Platforms

    Fixes bugs:
    	- The %pipe% IODevice was omitted on System V platforms.
    	- The AXP VMS build script needed /NESTED_INCLUDE=PRIMARY in
    CC_QUAL to work around a bug in the DEC C compiler.

### Fonts

    Fixes bugs:
    	- gs_lev2.ps redefined .loadFontmap incorrectly.

### Interpreter

    Fixes bugs:
    	- stream_compact used memcpy even though the source and destination
    might overlap.
    	- filter applied to a closed file could cause a crash.

### Library

    Fixes bugs:
    	- putdeviceparams to a printer didn't close and reopen the device
    if only the page size or resolution was changed.

## Version 2.9.8 (6/20/94)

This is the first version that claims to be a full Level 2 implementation. It was distributed to satisfy a contractual requirement.

### Documentation

    In make.doc:
    	- Adds a reference to the generic System V section at the end of
    the SCO section.
    	- Notes that DEC OSF/1 systems may require changing the name of the
    install program to installbsd.

    Updates drivers.doc to reflect the change from "properties" to
    "parameters".

    Updates the Aladdin Enterprises Free Public License to version 1.

    In language.doc, notes that certain device parameters will be phased out.

### Procedures

    Fixes bugs:
    	- The file aa.ps was included in the distribution by mistake.

    Notes in the Unix makefiles that X11R6 probably needs SM and ICE added to
    XLIBS.

### Utilities

    Fixes bugs:
    	- viewjpeg.ps used a non-existent file as its example.
    	- A temporary string in wrfont.ps was allocated too small.

    Upgrades font2c.ps so it will handle (simple) Type 0 fonts as well as Type
    1.

### Drivers

    Fixes bugs:
    	- The TIFF drivers didn't byte-align each scan line.
    	- gdevtfax.c applied & to an array member of a structure.

    Changes the param_list interface slightly: Implementations of the
    put_params driver procedure should now use param_signal_error to report
    errors, and should not give up at the first error.  (Even though this is a
    non-backward-compatible change, old implementations will continue to work;
    they just won't deliver complete results to the setpagedevice Policies
    machinery.)

### Platforms

    Fixes bugs:
    	- Removes the time zone adjustment from gp_get_clock in gp_unix.c,
    since the value returned by all Unix systems is bogus.
    	- The DV/X makefile still included the dfaxhigh and dfaxlow drivers.
    	- gssetmod.com (VMS command file) didn't work properly if the
    argument list was empty.
    	- vms.mak, vms-axp.mak, and modules.lis hadn't been updated to
    reflect changes in 2.9.7.
    	- The MS Windows version wouldn't link (overflowed the 64K primary
    data segment).

### Fonts

    Makes the font substitution algorithm somewhat more intelligent.

### Interpreter

    Fixes bugs:
    	- Enumerating the pointers of a zero-length array of structures
    caused a divide by zero.
    	- iref.h didn't protect itself against multiple inclusion.
    	- The CCITTFaxEncode filter didn't byte-align the final
    end-of-block code if EndOfBlock and EncodedByteAlign were both true.
    	- make_initial_dict in iinit.c used `name' as a formal parameter
    name, which some compilers believe conflicts with a typedef.
    	- Not all internal operators had registered names.
    	- The GC used memcpy, rather than bytes_copy, when compacting
    objects, even though the source and destination might overlap.
    	- When debugging was enabled, gc_string_mark could give a spurious
    error indication.
    	- vmstatus returned too small a value for the maximum VM.
    	- The scanner could get into a loop when reading a radix-85 string.
    	- The GC could get into a state where it was called after every
    allocation (because of the patch setting global = true in ireclaim).
    	- The general path filling algorithm didn't skip regions that were
    completely outside the clipping box.
    	- The gs_screen_enum structure contained a pointer (porder) that
    pointed into the middle of a structure, confusing the GC.

    Implements the BitmapWidths flag in fonts.  The default of false means that
    we use scalable widths even with xfonts.

    Changes the Generic resource category so that ResourceFileName is optional.

    Changes the .getdeviceparams operator so that it takes an optional
    dictionary giving the set of keys whose values are wanted.  Changes the
    .putdeviceparams operator so that it takes an optional policy dictionary
    specifying the action to be taken on errors, and returns a list of keys and
    errors if it fails, rather than causing an error.  These are
    non-backward-compatible changes, but ordinary programs do not use these
    operators.

    Changes the names of some internal operators and procedures by adding
    a . to the beginning:
    	currenttime
    	devicename

    Implements currentpagedevice, and a small subset of setpagedevice.  Only
    the following keys in the page device dictionary are known to the current
    implementation, and the ones marked with * are not actually processed:
    	PageSize
    	InputAttributes
    	MediaColor, MediaWeight, MediaType, InsertSheet
    	  (for InputAttributes matching only)
    	*ImagingBBox
    	OutputAttributes
    	OutputType
    	  (for OutputAttributes matching only)
    	NumCopies
    	HWResolution
    	*Margins
    	*Orientation (for all devices, not just roll devices)
    	Policies
    	Install
    	BeginPage
    	EndPage
    Does not implement:
    	- Updating InputAttributes or OutputAttributes by sensing the state
    	  of the device;
    	- Retrying media matching after an initial failure;
    	- Automatic handling of portrait vs. landscape page size;
    	- Recording the CTM after Install as the one to be used for
    	  defaultmatrix, initmatrix, and initgraphics.
    Also, media matching is normally disabled (with InputAttributes = null)
    for all devices.  ****** We had to disable setpagedevice just before
    shipping this release, because of interactions with the older device
    handling machinery that we could not fix in the time available.

### Library

    Fixes bugs:
    	- 24-bit color (mem_true24_fill_rectangle and _copy_mono) had
    algorithm bugs.
    	- A complex conditional expression in gx_render_gray wouldn't
    compile properly with the DECStation 3100 Ultrix 4.3 compiler.
    	- The GC routines for gx_device_clip didn't handle the case where
    the 'current' pointer pointed to list.single.
    	- gx_add_char_bits used memcpy, rather than bytes_copy, for
    compressing character bitmaps, even though the source and destination might
    overlap.
    	- Some compilers require the definition of st_gstate_contents to
    precede the definitions of the GC procedures.
    	- Filling a large rectangle (more than 1K of bitmap) with a colored
    halftone overwrote random areas of the stack.

    Changes gs_setcachedevice[2] to take a pointer to an array of floats,
    rather than 6 or 10 individual floats.  THIS IS A NON-BACKWARD-COMPATIBLE
    CHANGE.

    Implements the BitmapWidths flag in fonts.

## Version 2.9.7-beta (6/5/94)

Yet another pre-3.0 beta. The main features are a fairly reliable garbage collector, and function prototypes almost everywhere they are needed.

### Documentation

    Fixes bugs:
    	- The comment at the beginning of the zfindlibfile procedure was
    incorrect.

    Replaces the GNU License (the COPYING file) with version 0 of the new
    Aladdin Enterprises Free Public License (the PUBLIC file).

### Procedures

    Fixes bugs:
    	- The definition of cmykread.dev in gs.mak was incorrect (it
    modified color.dev).

    Adds the ability to specify a value for FONTPATH on the command line
    (-sFONTPATH=), overriding GS_FONTPATH.

    Replaces the -oper2 configuration resource type with the ability to specify
    in the op_def list the dictionary in which operators will be defined.  (See
    opdef.h for more details.)  This is an internal change only.

### Utilities

    Fixes bugs:
    	- viewgif.ps got an error on interlaced GIF files whose height
    wasn't a multiple of 8.

    Changes traceop.ps so it stores the traced operator in the same dictionary
    where the operator is currently defined, if possible.

### Drivers

    Fixes bugs:
    	- The new G3 fax drivers crashed on page widths greater than 2623
    (40 * 64 + 63) pixels.  (We fixed this by disallowing page widths greater
    than approximately twice this.)
    	- The 24-bit PCX driver had some debugging code accidentally left
    in it that produced large volumes of useless console output.

    Removes the previous (Leffler) TIFF/F driver and the TruFax driver.

### Platforms

    Fixes bugs:
    	- time_.h, gp_unix.c, and gp_sysv.c didn't do the right thing on
    SVR4 platforms, where gettimeofday only takes 1 argument.
    	- The final linking command on Turbo C platforms didn't specify the
    COMPDIR directory for the linker.

### Fonts

    Changes the standard Fontmap to use the URW contributed fonts as
    work-alikes for Helvetica and Times Roman.

### Interpreter

    Fixes bugs:
    	- The garbage collector wasn't in a consistent state.
    	- In Level 2 mode, statusdict was allocated in global VM rather
    than local VM.
    	- resourceforall gave an error on the built-in categories such as
    Filter.
    	- The file searching algorithm didn't check the current directory
    first.
    	- When opening a file failed, it didn't return a different error
    depending on the problem.
    	- The CCITTFaxEncode filter crashed on widths larger than 2623 (64
    * 40 + 63) pixels.  (We fixed this by disallowing page widths greater than
    approximately twice this.)
    	- The .type1getsbw operator gave an invalidfont error if a
    CharString started with anything other than a [h]sbw.  (Adobe's published
    specs say this is invalid, but some Adobe MultiMaster fonts start with a
    callsubr and/or a callothersubr.)
    	- When printing out the stack with == after an error, the error
    handler got a repeated (and ultimately fatal) typecheck error if it
    encountered an object of non-standard type.
    	- The token operator could incorrectly attempt to free a structure
    on the stack if it encountered an input buffer boundary.
    	- string_to_ref didn't correctly set the a_local flag in the string
    object it created.
    	- If the -c switch was the last switch on the command line,
    Ghostscript always exited without going into interactive mode.
    	- copy didn't check for errors when copying a dictionary.

    Makes many minor changes (mostly adding prototypes) to reduce error and
    warning messages from gcc and other strict compilers.

    Adds files containing the 4 predefined PDF encodings (MacRoman, MacExpert,
    WinAnsi, and PDFDoc).

### Library

    Fixes bugs:
    	- image_bbox in gxccman.c could produce a division by 0 if a
    0-width character was being entered into the cache.
    	- gx_image_cached_char incorrectly specified a scale of 2x2 rather
    than 1x1 if it had to read bits from an xfont.
    	- Stale pointers in the halftone cache weren't cleared properly by
    a restore.  (We fixed this by making grestoreall clear the halftone cache.)
    	- setdash used gs_malloc, rather than the current allocator, for
    allocating the dash pattern.
    	- If one attempted to fill a very wide region with a colored
    halftone, gx_dc_ht_colored_fill_rectangle would loop indefinitely.
    	- The container_offset in clipping devices was set incorrectly,
    causing the garbage collector to mangle pointers.

    Changes the fopen routine in IODevices so that it can return an arbitrary
    error code, rather than simply succeeding or failing.  THIS IS A
    NON-BACKWARD-COMPATIBLE CHANGE.  It only affects IODevice implementations,
    of which there are very few.  (It doesn't affect ordinary device drivers.)

    Changes the char_metrics xfont procedure so it returns the width as
    floating point numbers rather than integers.  THIS IS A
    NON-BACKWARD-COMPATIBLE CHANGE.  It only affects xfont implementations, of
    which there are very few.

    Makes many minor changes (mostly adding prototypes) to reduce error and
    warning messages from gcc and other strict compilers.

## Version 2.9.6-beta (5/23/94, not distributed to the public)

This, too, was supposed to be the last beta release for public release 3.0. It was created primarily for a user who desperately needed a Level 1 system that would run properly on a 64-bit hardware architecture. The garbage collector is badly broken (it's in the middle of an architectural change); setpagedevice is still not implemented.

### Documentation

    Documents the standard location of Type 1 fonts on AIX.

    Changes the last few mentions of Ghostview for Microsoft Windows to GSview
    for Windows.

    Notes that Solaris 2.n provides the X11 header files in a different place.

    Changes README to reflect the differentiation between Aladdin Ghostscript
    and GNU Ghostscript.

### Procedures

    Fixes bugs:
    	- The compilation rules for the modules that call the IJG library
    used -Ijpeg rather than -I$(JPEGSRC).
    	- The rule for gslib.dev omitted echogs$(XE) as a prerequisite.

    Makes it possible to define the values of buildtime, copyright, revision,
    revisiondate, and serialnumber in the makefile.

### Utilities

    Fixes bugs:
    	- The viewgif.ps utility didn't handle local color tables.

    Updates ps2ai.ps to version 1.81.

### Drivers

    Fixes bugs:
    	- The TIFF and fax devices used some identical names, causing
    linker complaints.
    	- The bj10e/bj200 driver inadvertently disabled the sheet feeder.
    (The change may not actually fix this bug, since we don't have either of
    these printers with a sheet feeder to test it on.)
    	- The 'bit' device didn't map colors to pixel values correctly.
    	- The monochrome PCL driver didn't work around the fact that the
    Canon LBP4i printer didn't clear its seed row correctly.

    Adds new drivers:
    	- A user-contributed driver for the H-P DesignJet 650C.
    	- A user-contributed driver for the Canon LIPS III printer.
    	- A completely new tiffg3 driver with one based on the new, fast
    faxg3 code.  This driver does not include any external code, and carries an
    Aladdin copyright.
    	- A tiffg4 driver, also based on the fast CCITT filter code.

    Removes the tiffg3x driver that appeared briefly in 2.9.5, and renames the
    previous (Leffler) tiffg3 driver as tiffg3x.

    Adds support for A0, A1, and A2 paper sizes to PCL drivers.

    Changes all the names involving "props" to "params", for consistency with
    the header files, some other internal interfaces, and Adobe's terminology.
    THIS IS A NON-BACKWARD-COMPATIBLE CHANGE.  However, it only affects devices
    that implement their own get_props and put_props procedures, of which there
    aren't very many.

### Platforms

    Fixes bugs:
    	- The DV/X makefile used X11 rather than X for the X11 library name.
    	- The DV/X makefile incorrectly included the PC display drivers.
    	- The DV/X makefile omitted gp_dosfs.$(OBJ) from the list of
    platform-specific files.
    	- The DV/X makefile used : rather than ; for separating directory
    names in GS_LIB_DEFAULT.
    	- x_.h omitted a needed alias for XtAppSetFallbackResources.
    	- The makefile entry for System V Unix systems didn't include
    gp_unifn.$(OBJ).
    	- The comment before LDFLAGS in the gcc makefiles incorrectly
    suggested using the -x switch on Ultrix platforms.
    	- The forward declaration of quant_params in zfdct.c upset the Sun
    compiler because it declared a parameter as float rather than floatp.
    *	- The Microsoft C compiler, like the Borland C compilers, only
    compares the offset part of segmented pointers.

### Fonts

    Adds a fontmap suitable for use with Adobe Type Basics.

### Interpreter

    Fixes bugs:
    	- The STACK_LOOP_BEGIN macro in istack.h didn't work correctly on
    segmented systems.
    	- The end_phase procedure in igc.c didn't work correctly on
    segmented systems.
    	- Indexed color spaces didn't mark their base space properly when
    garbage collecting.
    	- The garbage collector didn't work on segmented systems, because
    it smashed the lsize field of large objects with mark/reloc information.
    	- Some structures didn't have correct associated GC procedures:
    gs_indexed_map, gs_client_pattern, gs_pattern_instance.
    	- restore could free names or stack segments that were still
    referenced.
    *	- If a packed object caused an error, the error object could be set
    to garbage rather than the correct object.
    *	- Badly designed error handlers which use $error for temporary
    storage could cause a dictfull error.
    	- Some compilers objected to the use of "dict" as a variable name
    in a scope where it was defined as a type.
    	- IODevices were declared const and non-const inconsistently.
    	- setpagedevice popped one object too many off the stack if the
    request included any subdictionaries that needed to be merged.
    	- More garbage collector bugs were fixed.
    	- If the current stack block was empty, Level 2 restore would give
    a spurious typecheck error.
    	- The CCITTFaxEncode filter could get confused if it emptied the
    input and filled the output at the same time.
    	- The CCITTFaxEncode filter could insert an extra EOL if it had to
    suspend at certain times.
    	- The new parser for literal strings (as of 2.9.5) could mis-count
    internal parentheses if a parenthesis caused the internal buffer collecting
    the string to overflow.
    	- If the current stack block had fewer than 3 elements,
    .type1addpath could report a spurious typecheck error.
    	- Text rendering operations (show, stringwidth, etc.) caused a
    crash if the current color was a Pattern that hadn't already been
    rasterized.
    	- If a program did a grestore when the graphics state stack was
    empty, the graphics state was initialized to unexpected (and, in some
    cases, invalid) values.
    	- pathforall could cause a bogus stackoverflow if it overflowed the
    current stack block.
    	- Closing an encoding filter with a procedure as target left the
    filter on the stack.
    *	- The outer loop in dict_lookup() could cause an addressing fault
    on segmented machines when looking up Level 2 operators, because the offset
    could get decremented past 0.
    	- There was an = instead of an == in a test in scanner_reloc_ptrs.
    	- The call on gs_reloc_refs in sproc_reloc_ptrs in zfproc.c omitted
    the last (gcst) argument.

    (Re-)implements the 2-D case of CCITTFaxEncode, and fixes a couple of bugs
    in it.

    Adds DiffEncode and DiffDecode filters that implement color prediction for
    the PDF variant of the LZWDecode filter.

    Changes the specification of .oserrorstring to be similar to getenv,
    where, etc.  THIS IS A NON-BACKWARD-COMPATIBLE CHANGE; however, no
    user-written code should be using .oserrorstring.

    Adds oversampling for better character rasterizing.

### Library

    Fixes bugs:
    	- gx_dc_ht_colored_fill_rectangle gave a compiler warning because
    of a problem with const pointers.
    	- dfmul2fixed_vars (in gxfixed.h) omitted the & before vda on
    big-endian platforms, causing compilation errors.
    	- IODevices were declared const and non-const inconsistently.
    	- The Type 1 rasterizer never enabled overshoot suppression.
    	- stroke didn't fatten the line properly if stroke adjustment was
    enabled, or if the line was horizontal or vertical.
    *	- The clipping test for characters was too strict by almost 1
    pixel, leading to unnecessary clipping of text at the edge of the clipping
    box.
    *	- The initial clipping box was computed incorrectly for devices
    whose initial transformation matrix included a rotation.

    Changed the implementation of clipping lists and show enumerators to use
    separate objects rather than embedded objects, to pacify the GC.  (This is
    an internal change, not visible at the PostScript or API level.)

    Makes the character cache trim off left and right blank areas, as well as
    top and bottom.  (Internal change.)

    Adds oversampling for better character rasterizing.

## Version 2.9.5-beta (4/11/94)

This was supposed to be the last beta release before 3.0, but it won't be. The only known major defects are the unreliable garbage collector, and the dummy implementation of setpagedevice/currentpagedevice.

### Documentation

    Fixes bugs:
    	- The file commnew.doc didn't belong in the fileset.

    Notes in the makefiles that SVR4 systems may need to set EXTRALIBS=-lnsl.

    Adds a user-contributed `man' page for the ps2epsi utility.

### Procedures

    Fixes bugs:
    	- The IJG files didn't compile properly by themselves, because they
    didn't have $(AK) in their dependency list.

    Changes back the handling of files named on the command line, so that they
    are first sought in the current directory, and if that fails, use the
    search path.  (2.9.4-beta changed things so that files on the command line
    did not use the search path, because as of that version, the search path
    doesn't necessarily include the current directory.  I consider the "check
    the current directory and then use the search path" rule, which is the
    MS-DOS standard and was used in Ghostscript prior to 2.9.4, a serious
    mistake, since it is one of the best-known security holes in Unix and can
    also produce confusing and unexpected results depending on the current
    directory; I would much rather have a clear distinction between
    user-specified files, which should not use any path searching, and system
    files, that only use the defined search path.  However, as of this moment,
    users seem to want the convenience at the expense of insecurity and
    confusion.)

    Adds '.' to the beginning of the search path for MS-DOS platforms, to
    conform to the usual MS-DOS file searching convention.

    Adds a -c ("code") switch, which interprets following arguments (until the
    next switch) as PostScript tokens.

    Changes the handling of FEATURE_DEVS so that either level1.dev or
    level2.dev must normally be selected.  THIS IS A NON-BACKWARD-COMPATIBLE
    CHANGE for Level 1 systems, which formerly set FEATURE_DEVS to an empty
    definition.

### Utilities

    Fixes bugs:
    	- bench.ps didn't switch back to local VM properly before running
    the program being benchmarked.

    Adds a ppmsetpagesize command to the pstoppm utility.

### Drivers

    Fixes bugs:
    	- The PCX and GIF drivers used an incorrect algorithm for computing
    the blue component of the color palette, which could cause colors to come
    out with not quite enough blue.
    	- The SPARCprinter driver wouldn't compile with non-ANSI compilers.

    Adds new drivers:
    	- A user-contributed driver for DEC sixel displays like the VT240
    (sxlcrt, in gdevln03.c, which has a FSF copyright.)
    	- A much larger and supposedly faster version of the TIFF/F driver
    (tiffg3x, in gdevtifx.c), contributed by a user.  This has the same
    copyright as the TIFF/F driver (gdevtiff.c).
    	- A driver (faxg3, in gdevfax.c) that produces plain Group 3 fax
    output with no header, using the CCITTFaxEncode filter to do the work.
    (This is around 2.5-3 times as fast as the other fax drivers distributed
    with Ghostscript.)
    	- A user-contributed driver for the Mitsubishi CP50 color printer.

    Changes the `bit' driver so one can set the Colors and *Values properties.

    Makes the color mapping for PC displays, PCX files, and GIF files identical
    (they differed slightly before).

### Platforms

    Fixes bugs:
    	- VMS used DISPLAY rather than DECW$DISPLAY to get the display name
    if opening the display failed.
    	- Many minor bugs relating to OS/2 and Win32 were fixed.
    	- On Unix and DV/X platforms, the install script didn't mkdir
    $(gsdir), and didn't mkdir the intermediate directory for the man page.
    	- On BSD and UTek platforms, the declaration of memset in
    memory_.h, and the definition in gsmisc.c, conflicted with the ANSI
    declaration.
    	- One of the SPARC compilers compiled the intersection computation
    in arc_either (gspath.c) incorrectly.
    	- The temporary file names created under OS/2 could exceed the 8.3
    length limit.

### Interpreter

    Fixes bugs:
    	- The test files for the IJG library had been damaged by EOL
    conversion.
    	- The garbage collector didn't mark some of the most recently
    created names.
    	- The interpreter would sometimes report a typecheck instead of a
    stackunderflow.
    	- If aload didn't have enough room on the stack, it would report a
    rangecheck rather than a stackoverflow.
    	- zcontext wouldn't compile, because it hadn't been updated to the
    new GC interfaces.
    	- The definition of private_st_stream_proc_state in ifilter.h ended
    with a semicolon, which upset some compilers.
    	- load didn't check to make sure that the dictionaries it examined
    had read access.
    	- cvrs didn't handle negative numbers in radix 2 or 3 properly.
    	- The allocator could become confused if it was asked to allocate a
    large array.
    	- readline gave an ioerror rather than a rangecheck if it
    overflowed the string.
    	- The allocator didn't free packed arrays properly.
    	- The allocator's check for LIFO freeing of arrays was off by 1, so
    it never succeeded.
    	- The undercolor removal and black generation procedures weren't
    initialized properly.
    	- If the interpreter couldn't find gs_init.ps, it returned a random
    exit code.
    	- If an operator expected a procedure and didn't get one, it
    sometimes gave an invalidaccess rather than a typecheck.
    	- Unix file enumeration often did the wrong thing if there were
    directories in the pattern.
    	- The ASCIIHexDecode filter read an extra character after the
    terminating >.
    	- scalefont didn't fill in ScaleMatrix properly.
    	- The CCITTFaxEncode filter crashed if the width of the page wasn't
    a multiple of 8 bits.
    	- The error printing code used .languagelevel, which wasn't defined
    in Level 1 configurations.
    	- setpagedevice didn't pop its argument.
    	- Definitions in statusdict didn't change according to the current
    language level.
    	- Separation color spaces didn't allow strings as color space names.
    	- Due to a bug in chunk_locate_ptr, the garbage collector sometimes
    decided incorrectly that a pointer was pointing outside collectable space.
    	- (Many other garbage collector bugs were fixed.)

    Implements additional Level 2 features:
    	- Garbage collection for strings.
    	- Expandable operand and dictionary stacks, and the ability to set
    	the maximum size of these stacks.
    	- Additional user and system parameters.  The following are dummies:
    	AccurateScreens, JobName, JobTimeout, WaitTimeout.
    	- Procedure-based filters usable with cvx/exec and token.
    	- Separation color spaces (always using the alternate space).
    	(These were theoretically implemented in version 2.6, but they were
    	never tested and were actually missing most of the implementation.)
    	- VMThreshold and VMReclaim for invoking GC automatically.

    Adds a hook in iscan.c for parsing DSC comments.

    Adds encoding and decoding filters for the BCP and TBCP protocols.  These
    are not fully implemented yet:
    	- The interrupt and status request characters are ignored on input,
    	and never generated on output;
    	- The TBCP encoder doesn't emit the start-of-protocol string;
    	- The TBCP decoder doesn't recognize the end-of-protocol string.

    Factors out Type 1 font capability as a separate feature.

    Changes the names of some files:
    	packed.h to ipacked.h;
    	bnum.h to ibnum.h.

    Changes the name of the value.index member of a ref to value.boolval.
    (Internal change only.)

### Library

    Fixes bugs:
    	- The definition of RELOC_PTRS_BEGIN in gsstruct.h wouldn't compile
    properly with non-ANSI compilers.
    	- The JPEG library wouldn't compile properly with non-ANSI compilers.
    *	- The platform font machinery gave up too easily in some cases.
    	- CMYK devices needing halftoning converted the CMYK color to RGB.
    	- The debugging code in arc_add (gspath.c) didn't print the output
    values correctly.

    Factors out Type 1 font capability as a separate feature.

## Version 2.9.4-beta (2/19/94)

### Procedures

    Changes Ghostscript's path searching algorithm so that it does not
    automatically look in the current directory first.  (The former algorithm
    was more MS-DOS-like; the new one is more Unix-like.)  If you want to
    include the current directory, you must include '.' in the search path.
    THIS IS A NON-BACKWARD-COMPATIBLE CHANGE.

    Adds two new resource types for genconf.c:
    	- -header filexxx.h adds #include "filexxx.h" to gconfig.h.
    	- -libpath dir adds dir to the list of library search paths.

### Utilities

    Fixes bugs:
    	- impath.ps (used by bdftops) computed the starting X coordinate
    incorrectly, typically causing characters to be displaced slightly to the
    right.
    	- pstoppm.ps didn't handle local and global VM properly.

    Adds a ps2ai.ps utility, contributed by a user, for converting arbitrary
    PostScript files into a form compatible with Adobe Illustrator.

### Drivers

    Adds new drivers:
    	- A user-contributed driver for Imagen Impress laser printers.
    	- A user-contributed driver for the DEC LA75plus printer.

### Platforms

    Under OS/2, adds the ability to keep Ghostscript in memory for a
    specified number of minutes.

    Adds support for Win32 and Win32s.

    Changes the MS Windows platform font interface so that it does not attempt
    to render fonts at sizes smaller than 6 pixels.  Changes the X Windows
    interface, which already did this for 4-point and smaller fonts, to also
    use a lower limit of 6 pixels.  Also changes the X Windows platform font
    machinery so it does not render fonts at sizes larger than 36 pixels: at
    large sizes, Ghostscript does a perfectly good job, and some X font servers
    rasterize the entire font and lock up the entire window system while doing
    so.

### Interpreter

    Fixes bugs:
    	- currentdash always returned a new array of reals, rather than the
    actual argument of setdash.
    	- Strings in binary object sequences read in as integers.
    	- Because of a bug in chunk_locate_ptr, some large objects didn't
    get freed properly.
    	- If an error occurred while processing an image, Ghostscript would
    attempt to free random blocks of storage.
    	- Input filters discarded trailing data, rather than filling it out
    with zeros.  (This is now fixed for ASCIIHexDecode and ASCII85Decode; it's
    not clear what other filters it should affect.)
    	- The ASCII85Encode filter produced garbage output for the final
    1-4 bytes before EOD.
    *	- The TIFF output driver produced incorrect output for the second
    and subsequent pages if the output was being produced on multiple files.
    *	- The default handleerror did a 'stop', which was not correct.
    	- gpcheck.h converted all positive return codes to 0 if interrupt
    checking was enabled.
    	- Images with multiple data sources didn't work.
    	- Images with 12-bit sample values didn't work.
    	- Images with a file as the data source read additional data beyond
    what was required.
    	- 2 vmreclaim worked (pretty much), but 1 vmreclaim didn't.
    	- If %lineedit was opened multiple times, characters from later
    openings overwrote characters from earlier ones.
    	- token returned garbage for the "remaining string" result when
    reading from a string, if it actually read all of the string.  (New bug in
    2.9.2, probably.)

    Implements additional Level 2 features:
    	- DCTEncode and DCTDecode filters.
    	- Filters with procedures as the data source or target.
    	(Except for token and cvx/exec.)
    	- Garbage collection for names.

    Changes the error printout so that strings are always truncated at 200
    characters.

    For Level 2 systems, changes the initial setting of the object format
    parameter from 0 to an appropriate non-zero value.

    * Changes the .quit operator so that it takes two operands, an error object
    and an error code; if the latter is negative, the interpreter returns this
    as the error code, rather than e_Quit.

    Makes StandardEncoding and ISOLatin1Encoding arrays, rather than packed
    arrays, on large-memory systems, for compatibility with certain test
    suites.  Changes .registerencoding to accept arrays as well as packed
    arrays.

### Library

    Fixes bugs:
    	- Due to an error in cie_mult3, CIE-based colors were badly
    mis-mapped.
    *	- Very narrow (but not empty) rectangles would disappear.
    *	- Small halftone cells could smash the next higher entry in the
    halftone cache.
    	- The orientation algorithm in gxstroke.c still interchanged
    clockwise and counter-clockwise coordinate systems (after having been
    "fixed" at least 3 times).
    	- Stroking 1-pixel-wide lines shortened them, instead of
    lengthening them, if non-butt caps were requested.

    Refactors mem_mapped8_copy_mono because of limitations in the bcc32
    compiler.

## Version 2.9.3-beta (1/19/94)

This version was created for evaluation purposes for a few users who needed Level 2 capability; it was never released to anyone else, even beta testers.

### Documentation

    Fixes bugs:
    	- The description of psview and xpsview was incorrect.

### Procedures

    Changes the installation directories for Unix and similar systems to put
    Ghostscript data in $(datadir)/ghostscript/gs-NN.NN.NN rather than directly
    in $(datadir)/ghostscript.  (Fonts still go in $(datadir)/ghostscript/fonts.)

### Drivers

    Fixes bugs:
    	- Some spaces were incorrectly replaced with tabs in the help
    message in the 3B1 display driver.
    	- The BMP driver wrote a spurious scan line at the beginning
    of its output.
    	- The monochrome PCX driver had the two palette elements
    interchanged.

    Adds new drivers:
    	- A user-contributed driver for the Xerox XES printer format.  This
    has a FSF copyright.
    	- A user-contributed driver for the Epson AP3250 printer.  (This is
    the same as the Stylus 800, with slightly different margins.)
    	- A user-contributed driver for the DEC LA70 printer with some
    algorithms for improving text at low resolutions.  This has a FSF
    copyright.
    	- A user-contributed driver for an intermediate-resolution mode
    for 9-pin "Epson-compatible" printers.

    Changes the name of the Stylus 800 driver from escp2 to st800.

    Adds a compile-time flag to the Epson driver to cope with Panasonic 9-pin
    printers, which sometimes have trouble mixing graphics and tabs.

### Platforms

    Fixes bugs:
    	- The MS Windows driver (gp_mswin.c) referred to iodev.h rather
    than gxiodev.h.
    	- On Unix System V platforms, gp_unifs.c and gdevpipe.c were
    incorrectly omitted from the link list.
    	- (Some?) System V platforms don't have the S_ISDIR macro,
    requiring a change in stat_.h.
    	- The Unix `install' target didn't install gs_std_e.ps and
    gs_iso_e.ps.
    	- No MODULES.LIS file was provided for VMS.

    Adds Desqview/X makefiles that actually work.

    Documents the set of H-P-supplied patches needed to make H-P's
    compilers process Ghostscript.

    Changes the MS Windows driver so that if the user presses the Enter key
    while the image window has the focus, the text window will be brought to
    the top and made the active window.  This is useful when viewing a
    multi-page document with Ghostscript.

### Interpreter

    Fixes bugs:
    	- The definition of public_st_client_color() in gxccolor.h
    included an extraneous semicolon.
    	- The definition of private_st_AXD_state() in sfilter.h included an
    extraneous semicolon.
    	- saxx.c didn't include sfilter.h, which it needed for the
    definition of private_st_AXD_state().
    	- ialloc_struct failed to create a separate chunk if the structure
    was very large.
    	- setcolorspace didn't allocate the colorspace object in the same
    VM space as the graphics state, causing problems when the colorspace was
    freed.
    	- In rare circumstances, currentfile could return an empty array
    rather than a file.
    	- Dictionary keys were always allocated in global VM.
    	- If NOPLATFONTS was true, definefont didn't check whether the
    dictionary was read-only before trying to insert an ExactSize key.
    	- startjob could get an invalidaccess error, because serverdict was
    allocated in global VM.
    	- Using definefont with an already registered font created a
    circular list structure.
    	- If a PostScript procedure appeared as a CharString in a Type 1
    font, it was always called with the character name, never the character
    code.
    	- The SubFileDecode filter didn't work with a non-empty EOD string
    (went into an endless loop).  (Probably a new bug in 2.8.)
    	- save/restore didn't properly restore the maxlength of a
    dictionary, causing data to get smashed at random.  (New bug in 2.9.)
    	- save didn't mark objects as old, so a nested restore had no
    effect.  (New bug in 2.9.2.)
    	- After returning from an OtherSubrs callback, op_type1_free
    freed the saved interpreter state incorrectly.  (New bug in 2.7.)
    	- Level 1 configurations didn't work because .makeoperator gave an
    invalidaccess error.  (New bug in 2.9.2.)
    	- ASCII85 string literals didn't work.  (Probably a new bug in 2.8.)
    	- If the current global/local allocation mode was different at the
    end of a file than at the beginning, an addressing fault could occur
    (gs_unregister_root in gs_run_string).  (New bug in 2.9.2.)
    	- After a setfileposition on a file open for reading,
    fileposition would return an incorrect value, even though the stream
    was actually repositioned properly.

    Brings the dictionary unpacking code for the DCT filters into line with
    Adobe Technical Note 5116, which describes the Picky parameter for
    DCTDecode and the NoMarker, Resync, Blend, Picky, and Relax parameters for
    DCTEncode.

    Changes the .quit operator so that if given a negative argument, the
    interpreter returns this as the error code, rather than e_Quit.

    Changes the Ghostscript integer version number from 100P+10S+T to
    10000P+100S+T.

    Changes the default halftone screen for high-resolution devices, both
    black-and-white and color.

### Library

    Fixes bugs:
    	- The software floating multiply code used with USE_FPU=-1 only
    worked on little-endian platforms.
    	- Specifying a left side bearing to .type1addpath produced an
    inappropriate offset.

## Version 2.9.2-beta (1/2/94)

This version was distributed only to beta testers. It adds a garbage collector and full local and global VM support. It is the first version that sets languagelevel = 2, i.e., claims to be a Level 2 implementation.

### Documentation

    Fixes bugs:
    	- make.doc still referred to use_* variables in gdevx.c, and
    use.doc didn't explain the use* X resources.

    Notes that -Olimit=1000 is needed to compile Ghostscript on AXP systems
    under OSF/1 1.3.

### Utilities

    Fixes bugs:
    	- viewgif.ps did not work with interlaced images.
    	- font2c.ps omitted gsmemory.h from the #include list in compiled
    fonts.

### Drivers

    Fixes bugs:
    	- The MS Windows driver hadn't been updated to work with the
    new additions to the gx_device structure.
    	- The BMP file driver wrote one scan line too many.
    	- The cdj driver omitted an important cast to int in the error
    diffusion code (FSdither macro).

    Changes the SuperVGA drivers to recognize erasepage and reset the
    color table, like the X driver.

    Adds some fragmentary code to begin implementing the PostScript fax
    extensions.

### Platforms

    Fixes bugs:
    	- The procedure initializers for the MS Windows console I/O
    were missing the new reset element.
    	- The makefile entry in bcwin.mak used -fdev rather than -iodev.
    	- The Borland C++ makefiles exceeded MS-DOS's line length limit if
    the compiler files were in the standard Borland directory (BORLANDC).
    	- Some procedures weren't declared with prototypes in gp_vms.c.
    	- Some declarations had to be reordered to pacify the VAX compiler.
    	- Under MS Windows, Ghostscript didn't automatically de-iconify the
    text window to display messages on an error exit.
    	- The Unix makefile rule for gconfig_.h used echogs rather than
    ./echogs.
    	- The Microsoft C makefile referred to an obsolete file gs.tr.
    	- gp_unifs.c used strpbrk and strrchr, which some systems lack.

    Updates the OS/2 code and documentation for compatibility with the current
    Ghostscript version.

### Fonts

    Fixes bugs:
    	- The X11 .pfa fonts replaced their .gsf requirements in the
    fontmap, but not distributed with the previous (beta) release.

    Adds fontmaps appropriate for use with DEC Ultrix and OSF/1 systems.

### Interpreter

    Fixes bugs:
    	- 4-value entries in the Metrics dictionary were interpreted with
    the width and side bearing interchanged.
    	- Objects large enough to require their own chunk were not freed
    properly.
    	- The GS_FONTPATH scanner didn't deal with the possibility that
    opening a file might fail.
    	- The interrupt and timeout errors incorrectly pushed an error
    object on the operand stack.
    	- imagemask gave an error if it was invoked with a dictionary
    argument with a current color space with more than 1 parameter.
    	- definefont insisted that a new font not have a FID entry.
    	- Some places didn't cast char to byte when needed.
    	- An extra element was left on the stack when substituting the
    default font for a font whose file couldn't be found.
    	- The CCITTFaxDecode filter didn't allow the dictionary to be
    omitted.  (The Adobe documentation doesn't allow this, but Adobe
    implementations do.)
    	- When the input came from a pipe (`-') switch, opening a filter on
    currentfile that required more than 1 input byte to make progress would
    cause Ghostscript to hang (in sreadbuf).
    	- The interpreter didn't call gs_set_lib_paths before executing a
    compiled-in initialization file.
    	- A stream could be closed more than once.  (New bug in 2.8.)
    	- The LZW decoder produced incorrect output if a code string was
    too long to fit into a single output buffer.  (New bug as of 2.8.)

    Implements a special check in def to allow construction of systemdict,
    which is stored in global VM but references dictionaries in local VM.

    Implements additional Level 2 features:
    	- %null% and %ram% IODevices.
    	- startjob, exitserver.
    	- Local and global VM (finish).
    	- Garbage collection (for everything except names and strings).

    Moves the procedures for selecting paper size from systemdict to userdict.

    Sets languagelevel to 2 in Level 2 mode, since essentially all of
    Level 2 is now implemented.

    Factors out the Level 1 extended color facilities (CMYK color and
    colorimage) as a separate configuration feature.

    Adds some preliminary code to begin implementing the Adobe BCP and TBCP
    communication protocols.

    Changes the implementation of save and restore so that the bookkeeping
    structures are allocated in the new area, not the old.  (This is an
    internal change not visible at the PostScript level.)

### Library

    Fixes bugs:
    	- gdevprn used some preprocessor macros in formal argument
    lists that ansi2knr couldn't handle.
    	- pick_cell_size called gs_distance_transform with a 0 argument
    that non-ANSI compilers didn't automatically promote to floating point.
    	- gs_screen_init called hypot with integer arguments that
    non-ANSI compilers didn't automatically promote to floating point.
    	- Some places didn't cast char to byte when needed.
    	- The vx/vy origin adjustment for WMode=1 wasn't implemented.
    	- The pattern cache wasn't initialized properly.
    	- Composite fonts didn't properly decode strings that started with
    an escape sequence, which have a special (undocumented) decoding rule, and
    also didn't properly decode strings with multiple consecutive escape
    sequences.

    Factors out the Level 1 extended color facilities (CMYK color and
    colorimage) as a separate configuration feature.

## Version 2.9.1-beta (12/7/93)

This version was distributed only to beta testers.

### Utilities

    Adds a viewgif.ps utility to view GIF files.  The current version does not
    work with interlaced data, local color tables, or files containing more
    than one image.

### Interpreter

    Fixes bugs:
    	- putinterval and copy didn't do the right thing if the source and
    destination were aliases for overlapping sections of the same array or
    string.
    	- The DCT filter stub didn't allow the dictionary to be omitted.
    (The Adobe documentation doesn't allow this, but Adobe implementations
    do.)

    Adds an optional dictionary argument to the LZWDecode filter, containing
    InitialCodeLength, FirstBitLowOrder, BlockData, and EarlyChange entries.
    Setting these parameters appropriately allows reading (non-interlaced) GIF
    data directly.

### Library

    Fixes bugs:
    	- setdash produced inverted output if the pattern had an odd
    number of elements and the offset O had the property that L <= O mod
    2*L, where L was the sum of the pattern elements.

## Version 2.9-beta (12/6/93)

Like 2.7, this version was created to satisfy a contractual requirement, and will never be distributed to anyone other than the other party to the contract.

### Documentation

    Notes that Ghostscript runs on IBM PCs and compatibles under DR DOS
    6.0.

    Notes that Ghostscript will run on IBM PCs and compatibles with
    Hercules display cards if you redirect text output to a file.

    Notes that the alternate DeskJet 500C driver (djet500c) does not work
    on the 550C.

    Gives a list of system-specific directories where Type 1 fonts are
    likely to be installed, as a suggested setting for GS_FONTPATH.

### Procedures

    Changes the distribution script so that it stores all text files in the
    main source archive with Unix end-of-line conventions, but with DOS
    end-of-line conventions in the MS-DOS-specific archive.

    Changes the MS-DOS, MS Windows, and OS/2 makefiles so that 486SX and 486DX
    processors are different CPU_TYPEs.  (The former, designated by
    CPU_TYPE=485, does not include an on-chip FPU.)

    Adds a line to gs_init.ps which can be uncommented to select A4 as
    the default paper size.

    Adds a definable CFLAGS macro to the makefiles, allowing -DA4 to
    select A4 as the default paper size.

    Adds the H-P printer drivers to the standard Unix configurations.

### Utilities

    Fixes bugs:
    	- If there were no unencoded characters, prfont.ps would get
    an error.

    Changes ansi2knr to accept a wider range of function declaration syntax,
    and to not depend on any Ghostscript header files.

### Drivers

    Fixes bugs:
    	- Several drivers (DigiFax, Epson LQ-2550, NEC P6) didn't handle
    A4 paper width.
    	- The IBM ProPrinter wasn't being initialized properly.
    	- The Epson driver didn't work properly with compilers that
    insisted on 'char' being a signed type.
    	- The Epson driver ignored its end_string argument, producing
    incorrect end-of-page behavior on some printers.

    Adds new drivers:
    	- User-contributed drivers for Bellcore MGR (a window manager most
    commonly used with OS-9) devices.
    	- A user-contributed driver for the CIF file format.
    	- A user-contributed driver for the HP 2563B line printer.

    Changes the LaserJet 2p, 3, and 4 drivers so they set the initial position
    to (0,0) rather than (0,0.25").  (I don't remember why it was the other
    way.)

    Implements the PageCount property in all drivers, not just printer
    drivers.

    Introduces a new gx_tile_bitmap type, and changes the tile_rectangle
    device procedure to take it in place of gx_bitmap.  THIS IS A
    NON-BACKWARD-COMPATIBLE CHANGE.  However, it only affects devices that
    implement their own tile_rectangle procedures, of which there aren't very
    many.

### Platforms

    Fixes bugs:
    	- The VMS module lists referred to SDCTD and SDCTE instead of
    SDCT.
    	- The Unix install script tried to install the non-existent file
    readme.doc.
    	- Microsoft C does something bizarre with empty macro parameters,
    which caused a problem with the gs_struct_type_... macros.
    	- The Unix platforms didn't automatically handle the presence
    or absence of <dirent.h>.
    	- The DEC Alpha OSF/1 1.3 library lacks `const' in the prototype
    for popen, which requires a workaround.
    	- The DEC Alpha OSF/1 1.3 X Windows library uses `private' as a
    member name.

    Splits off gp_unifs.c, containing code common to "Unix-like" file systems.

    Adds a user-contributed OS-9 platform.

### Interpreter

    Fixes bugs:
    	- The currentfile cache wasn't updated properly if an executable
    file appeared in the middle of a procedure.  In particular, eexec-encoded
    .PFB fonts often didn't work.
    	- There was an extraneous `goto top' in scfd.c.
    	- An integer constant overflowed in iname.c.
    	- -2147483648 (i.e., -1 << 31) was converted to a float.
    	- eexec didn't skip the first 4 characters correctly if they were
    split across a buffer boundary.
    	- The font/matrix pair cache didn't properly free entries with only
    an XUID that was being deallocated.

    Implements additional Level 2 features:
    	- Patterns, makepattern, setpattern.
    	- IODevice resource, setdevparams, currentdevparams.
    	- OutputDevice resource, setpagedevice, currentpagedevice.
    	(Partially implemented.)

    Adds a new type t_struct to handle miscellaneous types that are allocated
    as objects and that the interpreter doesn't handle specially, and changes
    condition, fontID, gstate, lock, and save types to use t_struct.  (This is
    an internal change, not visible at the language level.)

    Moves the maxlength of a dictionary to its own ref, eliminating the "size
    of integer" hack.  (This is an internal change, not visible at the
    language level.)

    Adds the last OS error number to the error printout.

    Removes the obsolete framedevice operator.

    Implements resetfile (the only Level 1 operator not yet implemented!).

    Changes the name of the getdevice operator to .getdevice.

### Library

    Fixes bugs:
    	- A couple of necessary casts from char * to byte * were omitted.
    	- A Sun compiler required an extra cast to (void *) in the e1
    macro in clip_rect_enum_ptrs in gxcpath.c.
    	- The gx_dc_ procedures defined in gxdraw.c weren't marked as
    'private'.
    	- The number of "on" pixels in a halftone cell sometimes varied by
    1 from cell to cell.
    	- Mapping a gray level to CMYK didn't subtract it from 1 (to
    produce the K component).
    *	- charpath took hints into account.

    Shuffles the order of some declarations to pacify the VMS C compiler.

## Version 2.8-beta (11/10/93)

This version was distributed only to beta testers. It adds Type 0 font support. It also includes extensive redesign of streams (to eventually support procedure streams) and device properties (to eventually support get/setpagedevice and get/setdevparams).

### Documentation

    Notes the change in X11 foreground/background handling.

    Changes README so it no longer claims that Ghostscript works with X11R3.

    Notes (in devs.mak) that the cdjmono driver is the best one to use for the
    DeskJet 510.

### Procedures

    Fixes bugs:
    	- echogs wasn't always invoked with ./ on Unix systems.

    Changes the file name unix-ansi.mak to unixansi.mak, so it can be created
    on a MS-DOS system.

    Adds a new "feature", ccinit.dev, which compiles and links the
    initialization files (gs_*.ps) into the executable, just as ccfonts.dev
    compiles and links fonts.  If ccinit and ccfonts are both selected, the
    only external file needed at run time is Fontmap.  Note that you must have
    a working version of Ghostscript already in order to create a version that
    uses the ccinit feature, just as for ccfonts.

### Utilities

    Fixes bugs:
    	- the ps2image utility didn't put a %! on the first line of the
    output.

### Drivers

    Fixes bugs:
    	- The Hercules display driver didn't include definitions for
    outport2 and PAGE_HEIGHT_INCHES, which it uses.
    	- The BGI driver didn't call setactivepage or setvisualpage,
    which it needs to do in general.
    	- The Apple DMP driver declared dmp_print_page rather than
    appledmp_print_page, causing a compilation error.

    Changes the X11 driver so that it doesn't use the default foreground and
    background colors: you must set foreground and background explicitly for
    Ghostscript if you want them to be other than black and white
    respectively.

    Adds new user-contributed drivers for:
    	- The StarJet 48 inkjet printer;
    	- The Linux VGALIB display interface.
    	- OS/2 Presentation Manager.

    Changes the margins of the Epson driver to 0.2, 0.0, 0.0, 0.0, which
    more accurately reflect the printer's capabilities.

    Changes the get_props and put_props device procedures to take property
    list "objects" with a procedural interface, rather than a data structure
    interface.  THIS IS A NON-BACKWARD-COMPATIBLE CHANGE.  It affects all
    get_props and put_props procedures.  Fortunately, there were only a few
    devices that implemented their own get_props and put_props procedures (the
    H-P color printers, and the three window systems -- X Windows, MS Windows,
    and OS/2 PM).

### Platforms

    Fixes bugs:
    	- The meaning of the -p switch for the Watcom compile-and-link
    program was changed between Watcom C/386 versions 8.5 and 9.5, causing the
    make process to malfunction.
    	- The SCFTAB and SCFDTAB modules were omitted from the VMS link
    list.

    Adds user-contributed code for OS/2.

    Removes the assumption that an 80486 CPU implies the presence of hardware
    floating point, since the 486SX and Cyrix 486SLC don't have it.

### Fonts

    Fixes bugs:
    *	- The GS_FONTPATH scanner didn't recognize .PFB fonts beginning
    with %!PS-AdobeFont.
    *	- The GS_FONTPATH scanner often didn't recognize .PFB fonts at all.
    	- Type 1 fonts always set the line join, line cap, and miter limit
    to known values, rather than using the current values.  (Using the current
    values doesn't make much sense, but it's apparently what the Adobe
    implementations do.)
    	- DISKFONTS didn't work, because of the change in the Ghostscript
    fonts to do a systemdict begin/end (in version 2.7.1).

### Interpreter

    Fixes bugs:
    	- == didn't produce exactly the same output as the Adobe
    interpreters.  (Some automated debugging and testing programs care.)
    	- The CCITTFaxEncode filter could get caught in an infinite loop,
    because it failed to mask a byte datum when scanning for runs of black
    pixels.
    	- The write operator gave an error for values outside the range 0
    to 255, rather than just using the low-order 8 bits.
    	- Some applications call a statusdict procedure named
    setresolution without checking first whether it is present; Ghostscript
    didn't provide one.
    	- Reading from a closed stream caused an error instead of
    returning EOF.
    	- Input streams didn't close automatically at EOF.
    	- findfont was defined as an operator, not a procedure.
    	- closefile on a closed file gave an error.  (It isn't obvious
    that the Adobe documentation specifies that it shouldn't, but that's what
    Adobe says they do.)
    	- The LZWDecode filter didn't handle codes representing strings
    longer than the buffer size correctly.
    	- The LZWDecode filter only allowed 4095 codes to be used, rather
    than 4096.
    	- The rand operator produced an infinite string of zeros if
    given 0 or 0x7fffffff as the seed.
    	- When a CDevProc procedure was called, there was an extra
    copy of the character name on the operand stack below the operands of
    CDevProc.

    Replaces all stream implementations with new ones designed to allow
    interruption at arbitrary times.  ****** The 2-D case of CCITTFaxEncode
    hasn't been converted (but it probably didn't work before, either).

    Implements additional Level 2 features:
    	- Type 0 (composite) fonts.

    Adds an eexecEncode filter.

    Implements setcolorscreen, which was accidentally omitted from 2.7.

### Library

    Fixes bugs:
    *	- In colorimage, if the color space of the image was different
    from the current color space, and the first data values on a scan line
    were zeros, the wrong color could result.
    	- The new flatness testing algorithm could overflow, producing
    straight lines or obvious polygons instead of curves.
    	- Images could fail to display pixels after the first non-blank
    pixel on a line if halftoned color was required.  (This bug was probably
    introduced in 2.7.)
    	- Interpolation between transfer map entries didn't work, because
    of a rounding/truncation bug in frac2bits (bug introduced in 2.7.1.)
    	- cshow did an extra grestore at the end.

    * Implements a hack to slightly displace 1-bit-wide or -high images.  This
    is necessary to work around a bug in TeX (or dvips?), which uses such
    images to draw horizontal and vertical lines without positioning them to
    ensure that they cover device pixel centers.

    Adds support for composite fonts (no new client procedures).

## Version 2.7.2-beta (10/11/93)

This version was distributed only to alpha testers.

### Utilities

    Fixes bugs:
    	- prfont.ps didn't print unencoded characters.

    Improves mergeini.ps to remove embedded comments.

### Interpreter

    Fixes bugs:
    	- An error occurring within the scope of an internal .stopped
    didn't pop the command and error name off the stack.
    *	- The = and == procedures weren't re-entrant.

    * Adds a .writecvs operator that does a cvs to an internal string followed
    by a writestring.

### Library

    Fixes bugs:
    	- grestore freed the path and the clip path in an order that
    was likely to lead to memory sandbars.
    	- moveto + closepath didn't actually close the path.
    	- moveto + reversepath produced an empty path (no moveto).
    	- moveto + closepath + reversepath produced an extra lineto.
    	- reversepath didn't set the current point to the end (i.e., the
    former beginning) of the last subpath.

    Adds a "planar" memory device.

## Version 2.7.1-beta (10/4/93, not distributed to the public)

Like 2.7, this version was created to satisfy a contractual requirement, and will never be distributed to anyone other than the other party to the contract.

### Documentation

    Documents the GS_OPTIONS environment variable.

    Adds a summary of all environment variables to the documentation
    (use.doc).

    Documents the existence of a third free viewer built on Ghostscript.

### Utilities

    Fixes bugs:
    	- wrfont didn't wrap a systemdict begin / end around the body of
    the font.
    	- wrfont wrote out the Symbol and ZapfDingbats encodings in a way
    that only worked if the encoding was known by name.

    Changes bdftops to include an XUID if desired.

    Changes bdftops so that it uses 'show' for unknown ligatures, rather than
    executing the characters as subroutines; this makes such ligatures work
    properly with xfonts.

### Drivers

    Fixes bugs:
    	- The PCL drivers sent a printer reset (<ESC>E) at the beginning
    of every page, instead of only before the first page.
    	- The PCX driver didn't round up the scan line width in the
    header, even though it produced scan lines with the correct (rounded)
    number of bytes.

    Adds a new map_rgb_alpha_color procedure.  This is a backward-compatible
    change; this procedure defaults to calling map_rgb_color.

### Platforms

    Fixes bugs:
    	- On Unix platforms, the value of the TEMP environment variable
    had to end with a '/'.
    	- On MS-DOS systems, printer output to devices other than PRN
    (specifically, LPTn) didn't put the device into binary mode.

    Adds FPU_TYPE to the Unix makefiles, with a default value of 1.

    Removes the mention of Xmu linking problems on the SunOS platform,
    since the problem no longer exists.

    Changes the order of X Windows libraries from Xt X11 Xext to Xt Xext X11.
    This makes the OSF/1 linker happier.

### Fonts

    Fixes bugs:
    	- All the fonts originated by Aladdin, and the shareware fonts,
    had UniqueIDs in the 4xxxxxx range, which is only supposed to be used for
    limited-distribution fonts.
    *	- When Ghostscript loaded a font, it pushed a scratch dictionary
    on the dictionary stack, rather than userdict.  (Note that this fix also
    requires fixing the fonts to include a protective systemdict begin /
    end; see below.)
    *	- When loading a font failed, Ghostscript didn't check the font
    name against the default font name properly.
    	- Ghostscript's own fonts didn't include a systemdict begin /
    end to guard against redefinition of names used in the reading
    procedures (e.g., index).
    *	- When Ghostscript scanned a .PFB font to get the FontName, it
    didn't skip over the 6-byte header, which could cause confusion or a
    syntaxerror.
    	- Loading a .PFB font that left extra information on the
    operand stack didn't work.

    Changes the ZapfDingbats font to use DingbatsEncoding rather than include
    a copy of the encoding in itself, if DingbatsEncoding is known.  Changes
    the Symbol font similarly.

    Removes eexec encryption from the 4 URW fonts, so they will work with
    DISKFONTS.

    Adds shareware Hiragana and Katakana fonts (Calligraphic-Hiragana and
    Calligraphic-Katakana, by Kevin Hartig).

    Adds GS on the end of the family names of all of Aladdin's own converted
    fonts.

    Replaces many of the Hershey fonts with new ones (mostly Type 1) created
    by Thomas Wolff, who added accents, accented characters, and other
    non-alphabetics.  These too now have proper UniqueIDs.

### Interpreter

    Fixes bugs:
    *	- imagemask interpreted the Decode array incorrectly (inverted).
    	- Running out of memory when constructing a path incorrectly
    signalled a limitcheck rather than a VMerror.
    	- restore didn't purge uncached scaled fonts properly.

    Adds alpha (opacity) to the graphics state, and setalpha and
    currentalpha operators.

    Redefines erasepage in terms of a new .fillpage operator that fills
    the current page with the current color and then does a sync_output.

    Redefines setdevice and putdeviceprops in terms of new .setdevice and
    .putdeviceprops operators that return a boolean indicating whether the
    page needs to be erased.  With this change, operators that erase the page
    always call erasepage at the interpreter level rather than calling
    gs_erasepage directly.

### Library

    Fixes bugs:
    	- The null device allowed its size to be reset.
    	- clippath didn't establish a current point if the clipping
    path was empty.
    *	- The Type 1 font interpreter (gs_type1_interpret) flattened
    curves even if it was being invoked for charpath.
    	- Colored halftones usually didn't come out with the correct
    phase, and had several other problems.
    	- A show or charpath within a BuildChar procedure didn't work.
    	- Accented characters composed with seac used the base
    character width instead of the composed character width.  (The Adobe
    documentation says these must be the same, but some commercial fonts
    don't obey this.)
    	- setcurrentpoint in the accent of a character composed with
    seac didn't take the accent's displacement into account.

    Adds an alpha (coverage) value to the graphics state, and
    gs_setalpha/currentalpha procedures.  Currently Ghostscript just passes
    the alpha value to the driver; it doesn't attempt to emulate alpha
    handling if the driver doesn't support it.

    Redefines gs_erasepage to call gs_fillpage.

    Bypasses the fill code if the clipping box is empty.  This makes a big
    difference for stringwidth, and doesn't hurt anything else.

    Changes frac_1 from 0x7fff to 0x7ff8.  This allows exact representation of
    practically all useful fractions, since this number (32760) is
    2*2*2*3*3*5*7*13.

    Changes float to double in several matrix routines for better accuracy.

    Adds new device properties to implement the deviceinfo operator:
    Colors, GrayValues, RedValues, GreenValues, BlueValues, ColorValues.
    Also adds HWBitsPerPixel and HWColorMap.

    Changes the sorting algorithm for halftones to use qsort instead of
    special code.

    Changes the Type 1 interpreter so that it uses the current point, rather
    than (0,0), as the character origin.

## Version 2.7-beta (9/20/93, not distributed to the public)

This is the first of a series of beta-only versions planned for release between 2.6.n and 3.0. This version, in particular, was created to satisfy a contractual requirement, and will never be distributed to anyone other than the other party to the contract.

### Documentation

    Fixes bugs:
    	- The "HP XLFD extensions" to X11R5 are not specific to H-P
    platforms.
    	- The configuration generation script used rm rather than rm -f.
    	- gs.1 was installed in $(docdir) rather than $(mandir);
    $(mandir) wasn't defined.
    	- ansi2knr.1 was installed in $(docdir), which was
    inappropriate because ansi2knr itself wasn't installed anywhere.

    Moves documentation for versions 2.4.x and 2.5.x to history.doc.

    Moves the documentation on how to add devices to the configuration
    from devs.mak to make.doc.

    Changes the name of readme.doc to current.doc, since the presence of
    two "readme" files was confusing to users.

    Documents how to use the Microsoft Windows PostScript printer driver
    to convert TrueType fonts to Type 1 fonts embedded in the document.

    Corrects several errors in the documentation of the get_bits driver
    procedure.

    Documents the fact that X11R3 is no longer supported.

    Removes the last references to "Ghostscript" from the comments in the
    gs_*.ps files.  The only remaining reference, other than the boilerplate
    comments at the beginning of each file, is in the message at the end of
    gs_init.ps.

    Documents the use of WMAKEL rather than WMAKE with the Watcom compiler.

### Procedures

    Fixes bugs:
    *	- The Unix install script used gs rather than $(GS) as the name of
    the executable.
    *	- The Unix install script didn't copy gs_dbt_e.ps to $(gsdatadir).
    	- genconf.c used ps2 as a variable name; ps2 is a predefined
    preprocessor symbol in the VSC compiler used by IBM.
    	- @-expansion didn't interact properly with -- and -+.
    	- The Unix install script didn't copy COPYING to $(docdir),
    and copied README to $(gsdatadir) rather than $(docdir).
    	- ps2ascii used /bin/sh -f, which is an incorrect flag.

    Removes all uses and mentions of USG (a now-obsolete GNU convention)
    as a synonym for SYSV.

    Removes filter.dev and dps.dev from FEATURE_DEVS if level2.dev is
    included, since they don't add anything beyond level2.dev.

    Changes the ccgs script to explictly remove the old .o file before
    doing the mv, for the benefit of people who have changed mv to prompt
    before overwriting.  Changes the configuration script to use rm -f
    for the same reason.

    Changes the -Z switch so an empty list of options does nothing, rather
    than turning on all options.

    Adds a -@ switch which is like -- and -+ except that it does
    @-expansion of arguments.

    Changes genconf so it takes patterns from the command line that describe
    how to write the linker control files, rather than having the patterns
    built in.

    Changes -d and -D so that if no value is supplied, the default is
    true rather than null.

### Utilities

    Fixes bugs:
    *	- The ps2ascii script still referenced ps2ascii.ps under its
    old name gs_2asc.ps.
    *	- ps2image.ps had a 'pop' missing in the written-out
    definition of 'max' in the boilerplate code it put at the beginning
    of compressed files.
    *	- ps2image.ps got a typecheck if a scan line had no repeated
    data in it anywhere.
    	- wrfont.ps didn't handle CharStrings or Subrs that weren't
    strings.
    	- mergeini.ps produced an init file that incorrectly
    attempted to load the Symbol and Dingbats encodings dynamically.

    Removes the gsview.bat file, since it was confusingly named and not
    generally useful.

    Changes bdftops back to using encrypted CharStrings, for compatibility
    with Adobe interpreters, but also changes lenIV to 0, to save a little
    more space.

    Changes the traceop utility so it makes traced operators appear to be
    operators, and so it will replace a definition in systemdict if explicitly
    requested to do so and systemdict is writable.

    Adds a printafm utility for printing the metrics of fonts in AFM format.

### Drivers

    Fixes bugs:
    	- The cdj driver was missing a few type casts that were needed to
    satisfy pedantic compilers.
    	- For banded devices, many of the non-displaying target routines
    were getting called with the original device as the first argument, not
    the target device.  (This didn't make any difference in practice, because
    gdev_prn_open explicitly copied the non-rendering procedures back into the
    procedure vector.)
    *	- The X driver didn't catch and discard bogus errors on
    XFreeColors, which faulty servers generate.
    *	- The X driver gave up on color allocation too easily.
    *	- The X driver dynamic color table size could become negative.
    *	- x_lookup_font could return platform fonts of very small sizes,
    which have very inaccurate metrics.
    *	- The ESCP/2 driver was incorrectly named gdevescp2 in devs.mak.
    	- The Apple DMP driver used #if 0 / #endif instead of comment
    brackets, and was incorrectly named "dmp" instead of "appledmp" in
    the source code.
    *	- The X driver didn't free dynamic colors at the start of each page.
    *	- The X driver didn't bind foreground/background defaults tightly.
    *	- The X driver didn't check for GHOSTVIEW_COLORS properly.
    *	- The X driver freed too many colors if an allocation request failed.
    *	- The X driver didn't check return value of gs_malloc for being NULL.
    *	- The DeskJet/LaserJet driver used an incorrect command for
    end-of-page.
    *	- The DeskJet/LaserJet driver incorrectly reset the printer at the
    beginning of every page.
    *	- The PCX driver put an old version number in the header, and
    didn't pad scan lines to an even number of bytes.
    	- The BMP driver used a variable named `quad', which is a
    reserved word on some platforms.
    *	- The TIFF driver didn't handle A4 or B4 size paper correctly.
    *	- The X11 driver incorrectly demanded the Xmu library, which was
    not needed and which caused link errors on some versions of SunOS.
    *	- X11 font matching scheme was too loose, causing overlaps and
    other problems.
    *	- X11 Font Extensions (rotated and mirrored fonts) did not work
    properly on NCD terminals.
    *	- When freeing the rgb cube/gray ramp, the parameters to gs_free()
    did not exactly match the parameters to gs_malloc().
    *	- Ghostscript failed to warn the user when it could not allocate
    the original color cube/gray ramp and dropped back to a smaller
    cube/ramp, or from color to mono.
    *	- x_release could cause Ghostscript to fail if a font was freed
    after the device was closed.
    	- The X driver continued to ask the server for colors even after a
    request failed, causing colored images to display very slowly.

    * Adds a pcxgray driver to provide 8-bit gray scale output in PCX format.

    Adds a pcx24b driver to provide 24-bit RGB color PCX output.

    * Adds a LaserJet 4 driver.

    Adds a user-contributed driver for the DEC LA70 (very similar to the LA75).

    Substantially improves the performance of the PxM drivers by eliminating
    an unnecessary copying step and by writing each scan line with a single
    fwrite when possible.

    Moves the gray-scale and 24-bit RGB device color mapping routines to
    gxcmap.c from gdevpcx.c and (nowhere).

    Allows window granularities smaller than 64K in the VESA driver.

    Changes the LaserJet margins again.

### Platforms

    Fixes bugs:
    	- Platforms where stat doesn't return a st_blocks value
    computed the block count wrong.
    	- In gp_vms.c, the call on SYS$FILESCAN needed two uint *s
    rather than a long * and a struct *.
    *	- The VMS script files referenced IBSCAN instead of ISCAN2,
    and omitted GDEVXXF.
    *	- The UUENCODEd icons for the MS Windows platform were omitted
    from the fileset.
    *	- On MS-DOS systems, filenameforall didn't interpret * alone
    as a pattern matching all files.

    Adds wildcard matching capability to filenameforall under Unix.

    Removes gp_file_status from the platform interface, since all
    platforms provide identical stat calls in the C library.

    Adds DesqView/X (using djgcc and go32) as a platform.

    Removes the S3 driver from the standard PC configurations.

    Adds documentation for compiling Ghostscript on the Intergraph Clipper.

    Updates the documentation to add a better list of X Windows font
    names for the Sun platform.

### Fonts

    Creates an external file (gs_dbt_e.ps) with the ZapfDingbats encoding
    (actually in 2.6.1, but not documented there).

    Changes the names of the Cyrillic fonts to Shareware-Cyrillic-Regular
    and Shareware-Cyrillic-Italic, keeping Cyrillic, Cyrillic-Regular,
    and Cyrillic-Italic as aliases.

    * Removes the requirement that the FontName in the font file be the same
    as the name in Fontmap.  (This requirement led to the need for aliases,
    and was extremely confusing to users.)

    * Adds a GS_FONTPATH environment variable containing a list of directories
    that should be scanned automatically for fonts.

    * Gets rid of the Ugly font, and changes the default to the IBM Courier
    font, which is freely distributable.

### Interpreter

    Fixes bugs:
    	- cvs didn't check for stack underflow.
    *	- zht2.c didn't include alloc.h.
    *	- execstackoverflow cleared the e-stack instead of just
    cutting it back.
    	- if and ifelse incorrectly reported typecheck instead of
    stackunderflow.
    	- Copying a dictionary could alter some items even if a later
    item causes an invalidaccess error because of an attempted store of a
    local object into global VM.
    	- bitshift and cvrs assumed that longs occupied 32 bits.
    *	- exitserver didn't check the password, and always succeeded.
    	- Font loading didn't suppress all output messages if QUIET
    was set.
    *	- The interpreter incorrectly pushed its exit procedure on
    the e-stack if it was called again after an interrupt.
    *	- The interpreter didn't treat timeout like interrupt in
    terms of re-executing the current operation.
    *	- `show' operators popped their operands before they were
    sure they wouldn't be interrupted.
    *	- rotate with a matrix operand didn't check for multiples of
    90 degrees.
    	- In the system name table, ge was misspelled eg, and
    pathforall was misspelled pathfoall.
    *	- file_close_file attempted to free the buffer even if it was an
    externally supplied string (specifically, the argument of gs_run_string).
    	- setprintername (in gs_statd.ps) set printername rather than
    .printername.

    Implements additional Level 2 features:
    	- Indexed color space with lookup procedure.
    	- sethalftone, except for the transfer function override,
    	and currenthalftone.

    Implements OtherSubrs for indices greater than 3 (required for
    MultiMaster fonts).

    Implements black generation and undercolor removal.

    Changes `store' from a C procedure to a PostScript procedure.

    Changes idiv back so it requires integer operands, per the Adobe
    documentation but not per some old Adobe interpreters.

    * Adds many new paper sizes to gs_statd.ps.  It now includes ISO a0-a10
    and b0-b10, and CAD sizes archA-archE.

    Implements `status' for non-%os% files.  (This is currently a no-op,
    but the framework is there.)

    Changes the error handler so it normally uses = rather than == to print
    the operand stack, to avoid recursive errors.

    * Adds time slicing capability to the interpreter.

    Implements setcolorscreen/currentcolorscreen.

### Library

    Fixes bugs:
    *	- Rectangles with vertices specified in clockwise order were
    drawn as 0-width lines.
    *	- The string matching function reported that 'abcdefg'
    matched the pattern 'abcde'.
    *	- The bounding box of non-rectangular clipping paths was not
    being marked as valid, so cached characters would simply get
    discarded as being outside the bounding box.
    	- erasepage filled the page with the device's white color,
    not with gray level 1 passed through the transfer function.
    *	- Colors with equal R/G/B or C/M/Y components were rendered
    incorrectly if the 3 or 4 transfer functions were not all the same.
    *	- Because of a bug in rc_unshare, using CIE color would give
    random errors (such as /invalidaccess in --for--).
    *	- setbbox didn't round the coordinates properly, which could
    cause erroneous rangecheck errors with coordinates on the edge of the
    box.
    *	- Color halftones "flipped over" at the 50% point, inverting
    foreground and background.
    	- Quite a few places assumed that longs occupied 32 bits.
    *	- kshow passed an incorrect c1 value to the procedure.
    	- The debugging code in update_x_list in gxfill.c didn't take
    into account the possibility that the active line at x_first might be
    deleted.
    	- gx_image_cached_char called the xfont render_char procedure an
    extra time if it failed with required=0 and succeeded with required=1.
    (This was just a small inefficiency, not a logic bug.)
    	- Non-rectangular clipping regions weren't computed correctly,
    because accum_add_rect didn't handle overlapping rectangles.
    	- Drivers didn't report file system errors (such as file system
    full) as an ioerror.
    *	- setdevice didn't reset the charpath and setcachedevice flags.
    	- The Zortech compiler produced wrong code for the uid_equal
    macro; uid_equal is now a procedure.

    Passes OtherSubrs arguments back to the caller correctly for indices
    greater than 3.

    Implements black generation and undercolor removal.

    Removes gdev_mem_ensure_byte_order, which was no longer used or useful.

    Removes gstdev.c (device tracing), since it hasn't been used in a
    long time and is of little value given a reasonable debugger.

    Changes the interface to the xfont char_metrics and render_char
    procedures to allow them to return 1.

    Changes 32-bit memory devices so they use CMYK color mapping rather
    than RGB mapping with an unused byte.

    Implements gs_setcolorscreen/currentcolorscreen.

    Implements Level 2 halftones, except for the transfer function override.

    Implements a hack to make zero-width rectangles display as one pixel wide,
    to work around a bug in the Microsoft Windows PostScript driver.
    Currently the hack only works for vertical lines, not horizontal ones.

## Version 2.6.1 (5/28/93)

This is primarily a bug-fix release for 2.6, with a couple of minor additions.

### Documentation

    Adds proper `man' pages ansi2knr.1 and gs.1.

### Procedures

    Fixes bugs:
    	- The Unix makefile produced an incorrect linker command if
    EXTRALIBS was not empty.
    	- The Unix install commands didn't copy devices.doc,
    ps2epsi.doc, and xfonts.doc to the documentation directory.
    	- echogs.c didn't include <sys/types.h>, which is needed for
    time_t on some systems.
    	- malloc_.h used <malloc.h> rather than <stdlib.h> on
    NeXTStep systems.

    Changes the configuration procedure to use a C program rather than
    complex shell scripts.

### Utilities

    Fixes bugs:
    	- The boilerplate produced by ps2image used the 'max'
    operator, which is not a standard PostScript operator.
    	- The winmaps.ps utility had 'floring' instead of 'florin' in
    the OEMEncoding table.
    	- quit.ps was omitted from the PC distribution.

    Changes the name of the dicttomark procedure to .dicttomark.

    Renames gs_2asc.ps as ps2ascii.ps, so it matches the names of the
    script files.

### Drivers

    Fixes bugs:
    	- The pbmraw driver was writing out RGG instead of RGB values.
    	- The X11 driver used NULL in a place where it should have
    used None.
    	- For multi-file output, the GIF driver didn't write a header
    at the beginning of each file.
    	- The Epson driver didn't honor the -A4 compilation switch,
    didn't put (0,0) at the physical corner of the page, and was too
    liberal about using tabs instead of spaces.

    Replaces the color handling algorithms in the X Windows driver with
    new, much better ones.

    Makes the PC display drivers recognize the -A4 compilation switch,
    like the printer drivers.

    Adds new user-contributed drivers:
    	- A driver for Epson printers that use the ESC/P 2 control
    language, such as the Stylus 800.
    	- A driver for the Apple Dot Matrix Printer and Imagewriter.

    Adds a new get_xfont_device driver procedure.  This is a
    backward-compatible change, since there is a sensible default.

### Platforms

    Fixes bugs:
    	- On VMS, gconfig.h didn't have #include "gsconfig.h" as its
    first line.
    	- gconfig.c compiled incorrectly on the RS/6000 because the
    compiler evaluated a constant of the form (x<<y)+z incorrectly.
    	- Quite a few files that used the mem... functions didn't
    include memory_.h, which caused trouble on some bsd4.2 systems.
    	- The definition of zfont_char_xglyph confused one of the AIX
    compilers.
    	- On VMS, DEC C allows extra arguments for fopen, but gcc doesn't.
    	- On the MS Windows platform, 2.6 used gdevwddb rather than
    gdevwdib; the latter is almost always faster.
    	- The PC .zip files didn't include the Windows .ICO and .RES
    files in either GSEXE.ZIP or GSFILES.ZIP.

    On PC platforms, adds an option (FPU_TYPE=-1) to optimize for
    machines lacking a floating point processor.

### Fonts

    Adds 4 new fonts contributed by URW.  These have a URW copyright and
    are governed by the GNU License.

    Documents the fact that font names in Fontmap can be strings, not
    only names.

    Adds DingbatsEncoding as a predefined encoding (in addition to
    Standard, ISOLatin1, and Symbol).

### Interpreter

    Fixes bugs:
    	- memchr (used in zfile.c) isn't available on all platforms.
    	- languagelevel was defined as an operator rather than an
    integer.
    	- iccfont.c referred to name_StandardEncoding instead of
    #include'ing font.h and referring just to StandardEncoding.
    	- The CCITTFaxDecode filter didn't work on 32- (or 64-) bit
    machines, because of a bug in more_bits().
    	- The structures recording an allocation within the scope of
    a save could get allocated unnecessarily, because they weren't
    properly marked as free when an array was freed.

    Renames the following Ghostscript-specific operators by adding a '.'
    at the front: makeoperator, setdebug, setmaxlength, stringmatch,
    type1decrypt, type1encrypt.

    Adds a real implementation of glyphshow.

### Library

    Fixes bugs:
    	- Discarding fractional character coordinates in the Type 1
    rasterizer led to some rendering anomalies (e.g., characters 1 pixel
    too high).
    	- If a font had a non-standard encoding (i.e., not
    StandardEncoding, ISOLatin1Encoding, or SymbolEncoding), Ghostscript
    would never invoke the platform font code.
    	- The RGB to HSB color conversion algorithms produced
    nonsensical values.
    	- struct cached_char_s was defined redundantly in gxcdir.h,
    causing compilation problems on some systems.
    	- 32-bit color devices didn't work properly on little-endian
    machines (arrange_bytes in gdevmem2 was wrong).
    	- The scaled font cache could confuse two fonts with the same
    UniqueID and different Encodings.
    	- Under many common circumstances (first use of a character
    was with stringwidth, the font was renamed, the font encoding was
    changed), xfonts would not be used.

    Adds gs_glyphshow.

## Version 2.6 (5/9/93)

The main new feature in this release is the ability to use platform fonts. It also adds many more Level 2 PostScript facilities.

### Documentation

    Corrects some errors in the documentation of the makeimagedevice operator.

    Adds operand and result types to the comments at the beginning of all the
    operators.

    Adds new sections on installation in use.doc.

    Reinstates history.doc as a repository for old and no longer interesting
    history information.

    Adds a new file, devices.doc, with documentation for specific devices.

    Points out that font2c must be run with a Fontmap that includes the fonts
    being converted, and that its arguments must be quoted with "" on VMS
    systems.

    Notes that the font name in the Fontmap must be the same as the FontName
    in the font.

    Adds a list of the Level 2 facilities not provided by Ghostscript.

    Identifies bug-ghostscript@prep.ai.mit.edu as an alias for the
    gnu.ghostscript.bug newsgroup.

    Points out explicitly that -sOutputFile=- sends output to stdout, and
    requires using the -q switch.

    Documents the use of tar_cat to construct the Unix makefiles.

    Adds a new file, xfonts.doc, that describes the external font interface.

    Documents the fact that drivers must use gs_malloc and gs_free rather than
    malloc and free.

    Documents the *.sh (shell script) files.

    Adds brief documentation on some additional development tool .ps files.

    Documents the TEMP and GS_OPTIONS environment variable.

    Points out the need to run Windows in 386 Enhanced mode on machines
    that have less than 6 Mb of RAM.

    Consolidates documentation on compiler switches in make.doc (some of
    it had been in the unix*.mak files).

### Procedures

    Fixes bugs:
    	- \'s in arguments following -- were doubled.

    Includes the full set of filters automatically if the level2 feature
    is selected.

    Extends DEVICE_DEVS... up to DEVS9.  Adds DEVICE_DEVS1 as well.

    Renames turboc.mak and tbcplus.mak as tc.mak and bc.mak.

    Makes @-files use the library path (GS_LIB, -I).

    Changed the Unix install script to use install <file> <destfile>
    rather than install <file> <directory>.

    Adds a GS_OPTIONS environment variable that acts like an implicit @-file
    at the beginning of the command line (i.e., may contain switches and
    initialization files).

    Renames sym__enc.ps as gs_sym_e.ps.

    Adds a user-contributed shell script for using Ghostscript with an
    H-P printer spooler.

    Adds level1.ps to the set of installed utility files.

    Extends the TEMP environment variable (the directory for scratch
    files) to work on Unix as well as MS-DOS.

    Changes the MS Windows makefile to generate gswin.exe rather than
    gs.exe, and the Watcom makefile to generate gs386.exe.

    Moves the "product" string from gs_init.ps to iinit.c.

    Adds a GS macro to the makefiles, to allow choosing the name of the
    executable.

### Utilities

    Fixes bugs:
    *	- font2c did the wrong thing (still) for fonts that didn't
    use StandardEncoding, ISOLatin1Encoding, or SymbolEncoding.
    *	- impath.ps had a fatal bug (wrong operand order for
    charstack_write) that caused bdftops to fail.
    	- gslp didn't wrap or truncate lines.
    	- gslp didn't handle tabs in a second or subsequent column
    properly.
    	- The definition of ashow in gs_2asc.ps incorrectly undid the
    increment following the last character.
    	- The definition of awidthshow in gs_2asc.ps failed to pop
    two entries from the stack, and also tested the character against the
    wrong value.

    Adds a shell script (sysvlp.sh) that interfaces Ghostscript with the
    System V 3.2 lp interface.

    Adds ps2ascii and ps2epsi script/batch files.

    Adds a new utility, mergeini.ps, for concatenating all the
    Ghostscript initialization files into a single file, optionally
    removing comments and blank lines.

    Adds new switches to gslp:
    	-q: suppress all printed output.
    	--detect: check whether the file begins with %!, and if so,
    	    interpret it directly as a PostScript file.
    	--first-page <page#>: replaces the former -P switch.
    	--last-page <page#>: replaces the former -Q switch.
    	--(heading|footing)-(left|center|right) <string>: define
    	    headers/footers.  # inserts the page number.
    	--margin-(top|bottom|left|right) <inches>: define margins.
    	--spacing <n>: for double, triple, etc. spacing.
    Also makes gslp ignore all the enscript flags it doesn't implement.

    Adds an option to wrfont.ps to do encryption at read-in time.  (This
    allows much better compression of the standard Ghostscript fonts.)
    Changes bdftops to use this option.

    Changes gslp to accept wild cards in file names.

    Replaces landscap.ps with a new one contributed by a user.

    Changes the compression scheme used in ps2image to a much more
    effective one.  Writing images is much slower than with the previous
    scheme, but reading is not.

### Platforms

    Fixes bugs:
    	- SCFDTAB and SCFTAB were omitted from the VMS module lists.
    	- Function prototypes were not being used with the Watcom
    compiler.
    	- On MS-DOS platforms, if the value of the TEMP variable had
    a trailing : or \, Ghostscript appended a \ anyway.
    	- Under Windows, changing the size or resolution of the image
    closed and reopened the window.
    	- Ghostscript would not build correctly with the Watcom compiler
    if DOS4G=quiet was not set, because the DOS4GW copyright message was sent
    to stdout.
    *	- Finally gets Ghostscript to run properly on the RS/6000, by
    adding a compiler bug workaround to arc_add and arc_either.
    *	- Finally gets Ghostscript to compile properly on Sun SPARC
    systems, by adding a compiler bug workaround in scan_number.

    Changes the default MS-DOS configuration from 8086/8088 to 80286.

    Adds all the SuperVGA drivers to the BC++ and Watcom executables
    (except for the VESA driver in the Watcom executable).

    Adds a makefile (msc.mak) for the Microsoft C/C++ 7.0 platform.  This
    is currently a MS-DOS, not a MS Windows, platform.

    Changes gp_enumerate_files_init so it takes a gs_memory_procs *, not
    separate proc_alloc_t and proc_free_t arguments; also, it must
    enumerate precisely the requested set of files, not a superset.  THIS
    IS A NON-BACKWARD-COMPATIBLE CHANGE.  It affects all gp_*.c files.

    Adds the P*M drivers and bit.dev to the standard configuration on
    Unix platforms.

    Changes the Watcom makefile so it uses the WATCOM environment variable (by
    default) as the base directory for the Watcom executables.

    Adds the MS Windows COMMDLG.DLL and SHELL.DLL files to the set of
    files incorporated in GSEXE.ZIP, since the new MS Windows code uses
    them, and they aren't provided with Windows 3.0.

    Makes major revisions to the MS Windows platform and driver code, to
    support the gsview front end, and also to remove the dependence on the
    Borland EasyWin library.  NOTE: Compiling the MS Windows code now requires
    Borland C++ 3.1 (not 3.0).

    Changes time_.h so that Ghostscript will compile and run on A/UX.

    Changes the MS-DOS implementation of file enumeration so it always
    treats \s in the file name as literal characters, not escapes, unless
    there are two \\s in a row.  This does the most sensible thing given
    the DOS file naming conventions.

    Adds a %pipe% file device under Unix.

    Adds a makefile for Watcom C under MS Windows.  This is very preliminary;
    in particular, NO display output is supported.

### Fonts

    Fixes bugs:
    	- fonts.mak referred to ncri and puti rather than ncrri and
    putri.
    	- cyr and cyri had the wrong protection.
    	- The Hershey fonts left the font on the stack when they were
    loaded.
    *	- The FontName of an aliased font was the original FontName
    from the file, not the alias.
    *	- Fontmap.BTS had incorrect entries for AvantGarde-Demi and
    AvantGarde-DemiOblique.
    	- Ghostscript pushed userdict, rather than an empty writable
    dictionary, onto the stack when loading a font, leading to name clashes.

    Adds a new cfonts.mak with a full set of rules for compiling all the
    standard Ghostscript fonts (except the Hershey fonts) into C.

    Adds UniqueIDs to the Hershey fonts, and removes the UniqueIDs from
    the Hershey entries in the Fontmap.

    Adds a new Fontmap for VAX/VMS with DECWindows/Motif.

    Changes MakeHersheyFont so it takes the encoding as an additional
    parameter, and changes the Hershey-Symbol font to use SymbolEncoding.

### Drivers

    Fixes bugs:
    	- The !@*&^%#@$ PCL drivers *still* didn't do the right thing
    about vertical spacing: the <ESC>*p+<n>Y command works on all PCL 3,
    4, and 5 printers *except* the LaserJet IIp.
    	- The cdj driver used recursive macros (height, t_margin,
    b_margin) that not all compilers handled correctly.
    	- The djtc driver used some assignments including =*, which
    some compilers dislike.
    	- The S3 driver wouldn't compile correctly with the Watcom
    compiler.
    	- The makefile entry for the S3 driver was wrong.
    	- The SuperVGA drivers returned an error, rather than using
    the highest available resolution, if a too-high resolution was
    requested.
    	- The GIF driver produced an incorrect header for images
    wider or taller than 32K pixels.
    	- The GIF driver wasn't able to handle multi-page documents
    correctly.
    	- The margins on the DeskJet were still not correct.
    	- Some ANSI C compilers rejected a complex expression in
    gdevpccm.c.
    	- Printer drivers didn't recover cleanly from problems in
    opening the scratch files.
    	- The BJ-10e driver used the same name `out' for a label and
    a variable.
    	- The SCO ODT compiler couldn't handle sizeof(ppdev->fname).
    	- The Epson driver used the wrong value for ESC in the
    initialization string.

    Adds new drivers:
    	- Drivers to produce MS Windows .BMP format output.
    	- A new ATI Wonder display driver (800x600, 16 colors) and a
    1024x768 mode for the existing driver.

    Adds new user-contributed drivers:
    	- A driver for the Tektronix 4693d color printer.  This carries a
    university copyright.
    	- A driver for the SPARCprinter.
    	- A driver for the Canon BJ200 printer.
    	- A driver for the IBM ProPrinter.
    	- A driver for the DEC LJ250 printer, which has a
    PaintJet-compatible mode.
    	- A replacement driver for the Sony NWP533.
    	- A driver that writes TIFF/F (Group 3 fax) files.  This carries
    an external copyright.
    	- A driver for the C.Itoh M8510 printer.
    	- A driver for the Okidata MicroLine 182 9-pin dot-matrix printer.
    	- A Hercules Graphics driver.
    	- A driver for printers under MS Windows.
    	- A driver for direct frame buffer addressing under SCO Unix
    and Xenix and AT&T SVR4.

    Changes the get_bits driver procedure so it always reads a single
    scan line, and optionally does not copy the data.  THIS IS A
    NON-BACKWARD-COMPATIBLE CHANGE.  However, this change does not affect
    any existing printer driver, since these all go through intermediate
    routines in gdevprn.c.

    Changes gdevprn.h, and the relevant printer drivers, so that -DA4
    will change the default paper size for any printer driver.

    Allows the use of NULL or 0 for default procedures in the driver
    procedure vector.

    Adds an optional map_cmyk_color procedure to the driver procedure
    vector.

    Changes the Epson driver so that the minimum amount of white space
    required to use a tab is an easily changed parameter.

    Changes the BGI driver to use separate segments for the Borland
    device drivers, to reduce the risk of overflowing a segment.

    Adds an optimization option (normally enabled) to the PGM and PPM drivers
    such that they revert to PBM or (for PPM) PGM if the page can be
    represented that way.

    Adds a new (optional) driver procedure to get the procedure vector
    for external fonts.

    Adds an argument to gp_open_printer to indicate whether the file should be
    opened in binary or text mode.  THIS IS A NON-BACKWARD-COMPATIBLE CHANGE.
    However, this change does not affect any existing printer driver, since
    these all go through intermediate routines in gdevprn.c.

    Changes the LN03/LA50/LA75 driver so it uses a text record mode to open
    the output file under VMS (by adding an argument to gp_open_printer to
    indicate this.)

    Allows (indeed, encourages) drivers to use far_data to declare the device
    structure, primarily to avoid overflowing the 64K data segment under MS
    Windows.  Changes the file output drivers and many of the printer drivers
    to declare their device structures as far_data.

    Replaces the AT&T 3B1 driver with an updated version (from the same
    contributor).

    Changes the Epson BJ driver and the SPARCprinter driver so they align
    the (0,0) point of the page with the physical corner of the paper
    rather than with the origin of the printable area.

    Removes the EIZO MDB-10 driver, since it caused complications for the
    EGA and VGA drivers and is not a widely used device.

### Interpreter

    Fixes bugs:
    	- The entry for the copydevice operator in the operator table
    was initialized incorrectly.
    	- printobject and writeobject didn't handle nested arrays.
    	- restore didn't properly close the current file (if
    appropriate), causing an invalidaccess error.
    	- buildfont required the presence of a valid, 4-element
    FontBBox.  (The Red Books say it's required, but Adobe interpreters
    don't require it; some DEC software generates a 3-element FontBBox.)
    	- resourceforall had several bugs; it didn't do even
    approximately the right thing.  There were quite a few other problems
    with the implementation of resources.
    	- setfont, makefont, and scalefont would accept a font with
    no FID entry.
    *	- Loading a .PFB font left the file open (until the next
    restore or quit).
    	- The default (null) font didn't include a PaintType entry,
    which some PostScript files expected.
    *	- The ASCIIHexDecode filter sometimes thought the underlying
    stream was at EOF even when there was (at most one buffer's worth of)
    data left.
    	- iscan.c included <ctype.h> before std.h, causing type name
    clashes on some systems.
    *	- save and restore didn't handle the pointers in the graphics
    state correctly; for example, the current font wasn't restored
    properly.
    	- Binary object sequences at the top interpreter level didn't
    get executed immediately.
    	- On high-resolution devices, the default transfer function
    converted almost-white grays to very light grays rather than white.
    	- The `string' operator was checking the string length
    against max_uint rather than max_ushort, which could cause invalid
    lengths to be accepted.
    *	- deviceinfo caused a stackunderflow error.
    *	- idiv could give incorrect results for quotients or
    remainders that didn't fit in 24 bits.
    *	- The ASCII85Encode filter padded trailing bytes with 1's
    rather than 0's.
    *	- The ASCII85Decode filter had a typo that produced incorrect
    results if there were exactly 2 trailing bytes.
    	- findlibfile didn't push a copy of the file name if it was
    the name of a special (%) file.
    	- setduplexmode was not defined in statusdict, causing
    /undefined errors from some poorly designed input files.
    *	- The CCITTFaxDecode filter had several bugs in 2-D decoding.
    *	- The ASCII85Decode filter didn't read ahead to detect EOD if
    it fell precisely on a buffer boundary.
    	- If a file mentioned on the command line redefined `start',
    Ghostscript would run the new definition rather than the built-in one
    after processing all the files on the command line.
    	- The SCO ODT compiler couldn't handle the conditionals in the
    ngetc (iscan.c) and sgetc* (stream.h) macros.
    	- makefont and scalefont didn't cache the PostScript dictionaries
    for scaled fonts.
    	- Changing the elements of the Encoding of a font dynamically
    didn't take effect if the character was already cached.
    	- makefont and scalefont didn't add the (undocumented) OrigFont
    and ScaleMatrix entries to the new font.
    *	- findfont insisted that the font name be a string or a name.
    	- filenameforall could cause an incorrect transfer of control
    if no files matched the pattern.
    *	- ISOLatin1Encoding had hyphen instead of minus at code 45.
    	- restore didn't reset saved_cbot and saved_ctop correctly;
    as a result, some freed blocks could get abandoned rather than put on
    the free list.
    	- Some numerical constants in zarith.c assumed that longs
    occupied 32 bits.

    Implements additional Level 2 features:
    	- %device%file names (only the "os" device is provided).
    	- <~ ~> for ASCII-85 strings.
    	- Binary error messages.
    	- BuildGlyph.
    	- CCITTFaxDecode filter entries EndOfBlock, Rows, and
    	(undocumented) FirstBitLowOrder.
    	- {set/current}{color/colorspace/overprint/colorrendering/
    	blackgeneration/undercolorremoval}.  (See below under library
    	for limitations.)
    	- Decode for the dictionary form of image.
    	- File access modes a, r/w/a+.
    	- Font entries CDevProc, Metrics2, and WMode.
    	- Font operators cshow, findencoding, rootfont, and
    	setcachedevice2.
    	- glyphshow (emulated with PostScript code).
    	- languagelevel.
    	- realtime.
    	- setbbox.
    	- (Subset of) system and user parameters.
    	- xshow, yshow, and xyshow.
    	- XUIDs for fonts.

    Moves the installation of systemdict and the initial allocation of
    globaldict (if relevant) and userdict from gs_init.ps to iinit.c.

    Makes Level 2 features dynamically selectable through the
    .setlanguagelevel operator; disables all Level 2 features
    (specifically including automatic dictionary expansion) unless the
    level2 feature is included and active.

    Adds the .knownget operator for speeding up system procedures.

    Renames the type1addpath operator as .type1addpath; adds an optional
    left side bearing argument; changes it so it does not do the
    setcachedevice, fill, or stroke, but does do a moveto for the
    character width.  Changes Type1BuildChar appropriately.  (All this is
    needed to make WMode work.)

    Removes the .setmetrics operator, which is no longer needed.

    * Changes the meaning of the user_errors argument to gs_run_file and
    gs_run_string so that -1 means always return on an error, 0 means
    only return on an error not within a `stopped'.

    Adds all the necessary checks and operators for local/global VM, but
    doesn't actually implement local/global mode.

    Changes setcachedevice back so that it requires 4 numbers on the
    stack rather than a 4-element array.  (It was changed to be the other
    way in release 2.0, but that was because I didn't realize that fonts
    had to have an executable FontBBox, and some of the Ghostscript fonts
    didn't.)

    Changes all the filter operators from .filterxxx to .filter_xxx, and
    removes the need to enumerate them in gs_init.ps.

    Adds .oserrno and .oserrorstring operators for getting the last OS
    error (in the current context).

    Changes gs_finit similarly to gp_exit.  Adds gs_exit_with_code that
    takes both an exit status and a Ghostscript error code.

    Changes the name of name.h to iname.h.

    Adds support for the `interrupt' error (but doesn't provide any standard
    way of generating one, other than through the gp_check_interrupts polling
    function).

    Adds copyright to systemdict.

    Changes the spot halftone screen to an elliptical screen supplied by
    Berthold K. P. Horn.

    Adds a check that the first token in gs_init.ps is an integer.  In
    conjunction with other code in gs_init.ps, this should catch all attempts
    to run Ghostscript with a gs_init.ps that doesn't match the executable.

    Changes all relevant occurrences of sizeof to size_of in order to
    work with the buggy SVR4.2 C compiler.

    Changes gp_exit so it is passed both the Ghostscript error code and
    the exit status code as arguments.  This is backward-compatible for
    all but the pickiest compilers.

    Adds a call on gp_check_interrupts() after fwrite calls in the stream
    machinery.  This prevents lengthy console output from locking out
    other programs.

    Changes a couple of occurrences of op_def_ptr in iinit.c to work around a
    `const' bug in Sun's SC1.0 compiler.

    Adds a special hack in the 'where' operator to work around a bug in Aldus
    Freehand 2.x.

    Changes all empty argument lists from () to (void), which is the ANSI
    C syntax.

    Adds a hack to ignore ^[ and ^D^[ tokens, to work around the prologue
    and epilogue emitted by the MS Windows LaserJet IV driver.

    Defines the processcolors operator, which should not be needed, but
    is required because of bugs in Lotus 1-2-3 and Adobe PhotoShop.

    Changes the allocator (ialloc) to fill all allocated and/or freed
    blocks with a marker if gs_alloc_debug is set, as gs_malloc and
    gs_free already do.

### Library

    Fixes bugs:
    	- 16-bit memory devices stored the bytes of each pixel in the
    wrong order.
    	- copy_mono did the wrong thing when copying 1 source chunk
    to 2 destination chunks with polarity inverted.  (This probably
    didn't affect any actual uses of Ghostscript.)
    *	- The compile-time check for ints being 2 or 4 bytes used the
    #error directive, which most compilers don't recognize.
    	- arc and arcn didn't do the right thing for degenerate
    (single-point) arcs, or for arcs drawn in the "wrong" direction that
    were multiples of 360 degrees.
    	- charpath did the wrong thing with Type 3 fonts.
    	- copyscanlines gave an error if the buffer was too large.
    	- The copy_mono procedure (used for text and halftones) for
    2- and 4-bit-per-pixel memory and printer devices incorrectly
    incremented the destination pointer after every pixel, instead of
    only after every byte.
    	- The fill_rectangle procedure (used for graphics) for 2- and
    4-bit-per-pixel memory and printer devices, if given any color other
    than all 0's or all 1's, multiplied the X coordinate and width by 2
    or 4, thereby filling the wrong area.
    	- The use of 'data' in both gs_type1_data and gs_font upset
    the VMS compiler.
    	- The `Flex' feature wasn't implemented for Type 1 fonts,
    which caused serious errors in rendering some fonts that use it.
    (Unfortunately, some Adobe fonts violate the specification, so we had
    to implement Flex to always use a curve.)
    *	- Stem width adjustment was too eager, producing very strange
    effects on small characters with tight curves (a curve point could
    get snapped to the other side of the open area).
    	- The allocator didn't align structures adequately on
    machines where sizeof(long) or sizeof(char *) was 8 bytes.
    	- The test for IEEE floating point gave an incorrect
    (negative) result on machines where sizeof(long) was 8 bytes.
    	- genarch.c assumed that the result of subtracting two
    pointers was an int, leading to a garbage arch.h file on systems
    where this was false.
    *	- The Type 1 font interpreter incorrectly reset the adjusted
    path position to be the same as the unadjusted path position whenever
    it returned control to the client (in particular, for callothersubr),
    leading to discontinuities and distortions in the character shapes.
    *	- Accented characters in Type 1 fonts often misplaced the
    accent to the left.
    	- gsmisc.c wouldn't compile on machines with 64-bit pointers,
    because _pad was 0, and ANSI compilers don't accept 0-length arrays.
    	- pathforall got confused if the client procedures modified
    the path.
    	- The command list file representation limited X and Y
    coordinates to 15 bits.
    *	- stroke could produce spikes or other garbage for mitered
    joins as a result of stroke adjustment.
    	- The params_size field of the null device was wrong, so
    scaling the null device produced unpredictable results.

    Changes monobit memory devices to always store data big-endian.  This
    eliminates byte-swapping, at the cost of slightly slower rendering.

    Removes the memswab* routines, since they are no longer needed.

    Implements gs_cshow_[n_]init, which provides support for cshow, and
    gs_xyshow_[n_]init, which provides support for {x,y,xy}show.

    Adds an optional left side bearing argument to gs_type1_interpret.

    Changes gs_type1_interpret so it does not do a setcachedevice, fill,
    or stroke, but only appends the character outline to the path
    (including a moveto for the character width.)

    Removes gs_setmetrics, which is no longer needed.

    Implements gs_setcachedevice2, which provides support for
    setcachedevice2.

    Speeds up gsave/grestore by allocating, deallocating, and copying as
    much as possible of the graphics state in a single operation.

    Implements gs_{set/current}{color/colorspace/overprint/colorrendering/
    blackgeneration/undercolorremoval}.  Device, indexed (with table, not
    with procedure), CIE, and (substituted) separation colors are
    supported; some of the setup code for patterns is also present.

    Increases the size of temporary file names in gdevprn.h from 30
    characters to 60.

    Changes the character cache to be allocated dynamically in chunks.

    Splits gxcache.c into gxccache.c (fast "hit" code) and gxccman.c (all
    other code).

    Changes all occurrences of sizeof to size_of in order to work with the
    buggy SVR4.2 C compiler.

    Adds a new concept of "external fonts", which allow a driver to
    substitute its own fonts for the ones obtained through the normal
    font machinery.

    Changes all empty argument lists from () to (void), which is the ANSI
    C syntax.

## Version 2.5.2 (9/20/92)

This is yet another bug fix release to (finally!) get the PCL drivers working again.

### Procedures

    Fixes bugs:
    	- The comment in devs.mak for cdjcolor said it used 8 bits
    per pixel, rather than the correct 24.

    Adds gsbj/dj/lj/lp and gslp.ps to the installed files on Unix
    systems.

    Removes dps.dev and level2.dev from the standard configurations on
    all platforms, since the presence of the setcolor operator was
    causing the output of some common applications to fail.

### Utilities

    Fixes bugs:
    	- font2c produced invalid output for any font that didn't use
    StandardEncoding or ISOLatin1Encoding.

### Platforms

    Fixes bugs:
    	- gp_sysv.c required an extern long timezone.

### Drivers

    Fixes bugs:
    	- The PCL drivers were *still* doing the wrong thing about
    zeroing the seed row for Mode 3 compression.
    	- Setting the resolution with -r didn't work under Windows.
    	- The Windows driver got a stack overflow if it was ever
    asked to display a bit image wider than 32 pixels.
    	- The Tseng driver didn't sense the model (ET3000 vs. ET4000)
    correctly.

    Adds the eps9high device to the standard MS-DOS makefiles.

### Interpreter

    Fixes bugs:
    	- gs_run_string used gs_user_errors (a global) rather than
    user_errors (its argument) to control error handling.  (This does not
    affect normal operation of Ghostscript, only use as a server.)
    	- eexec popped the top element of the dictionary stack
    afterwards even if the encrypted code had pushed something onto it.
    This caused problems for some badly written PostScript code.
    	- The printed form of real numbers didn't always include a
    decimal point, causing compatibility problems.

    Makes -s and -d work for device properties.

    Increases the cache limit on large-memory systems.

    Adds a check to ensure that the revision of gs_init.ps matches that
    of the interpreter.

    Adds the .knownget operator.

### Library

    Fixes bugs:
    	- The raster computation in clist_render_init, and the
    computation of state_size in clist_open, didn't widen an operand to
    long, leading to possibly incorrect operation for 24-bit-per-pixel
    printers on MS-DOS systems.
    	- The flatness was set too large for Type 1 characters,
    leading to visible straight edges instead of curves at large sizes.
    	- Type 1 fonts that contained out-of-range coordinates would
    produce garbled output.  (This was not a problem with the standard
    Ghostscript fonts, or with Adobe Type Manager fonts.)
    	- gschar0.c wouldn't compile, because it referred to a
    non-existing structure member penum->chr.  (This had no effect on
    Ghostscript's operation.)
    	- The curve flattener required line segments to be no more
    than 8 x the flatness in length, leading to an enormous number of
    segments.
    	- pathforall would cause an addressing fault if the path
    consisted of only a moveto.

    Refactors some header files so that std.h is always included before
    any system header file that might include sys/types.h.

    Adds logic for removing top and bottom blank rows in cached
    characters.  (This is the beginning of compression for the cache.)

    Changes the arguments of memswab2/4 from char * to byte *, for more
    accurate type conformance.

## Version 2.5.1 (9/11/92)

This is the usual bug fix re-release.

### Procedures

    Fixes bugs:
    	- The makefile rules for compiled fonts had a circular
    dependency.
    	- `make begin' didn't work properly on all platforms.

    Ensures that all batch files end with a newline.  (The absence of the
    newline was confusing the GNU diff program.)

    Documents the fact that the -dASCIIOUT switch no longer exists.

### Utilities

    Fixes bugs:
    	- pstoppm didn't `bind' its internal procedures.
    	- grestoreall would undo the output device selected by
    pstoppm.

    Changes the utilities for reading and writing Type 1 character
    outlines so they can work with stack representations as well as
    arrays.

    Removes the pfbtogs.ps, phonbook.ps, and showpbm.ps utilities from
    the distribution.

    Adds a gslj utility to parallel gslp and gsdj.

### Platforms

    Adds the DeskJet 500C drivers (cdeskjet/cdj*) to the MS-DOS / Borland
    C++, MS-DOS / Watcom C/386, and MS-Windows configurations.

    Removes the PCX file driver from the MS Windows executable, because
    the static data segment exceeded 64K.

    Makes some changes in the Unix System V platform file (gp_sysv.c) and
    in time_.h and unixtail.mak to accommodate the 3B1.

### Fonts

    Fixes bugs:
    	- The Charter-Italic font was named bchi.pfa rather than
    bchri.pfa.
    	- The Cyrillic fonts (cyr.gsf, cyri.gsf) were omitted from
    the fileset.
    	- Ghostscript incorrectly assumed that all Type 1 fonts had a
    FontInfo dictionary.
    	- .loadfont used false PFBDecode, so a few .PFB fonts would
    get errors because the first eexec byte would be whitespace.

    Changes font2c and its supporting code so that compiled fonts are
    location-independent.

### Drivers

    Fixes bugs:
    	- The margins for the H-P printers were still wrong.
    	- The H-P drivers accidentally cleared the compression seed
    row when switching compression modes.
    	- Some of the H-P drivers used the wrong control codes for
    skipping blank lines.

    Adds user-supported drivers for the AT&T 3B1 console device, and for
    the NEC P6+ printer.

    Updates the SunView driver with a new version supplied by a(nother)
    user.

    Changes the X Windows driver so the Ghostscript window doesn't get
    input focus.

    Changes the common code for the printer drivers so that if it can
    allocate a full bitmap but there isn't at least a minimum amount of
    memory left afterwards, it switches to banding.

    Changes the Windows driver so it handles devices with more than 8
    bits per pixel.  (We haven't been able to test this.)

    Adds a read-only PageCount device property (for printer devices
    only).

    Changes all Aladdin-supported drivers to clip drawing requests to the
    ((0,0), (width,height)) rectangle of device space.

### Interpreter

    Fixes bugs:
    	- Closing a NullEncode filter always gave an ioerror.
    	- If a single-character name occurred 1 character before the
    end of an input buffer, the character would be doubled.
    	- The procedures in gs_statd.ps didn't use "bind".
    	- Setting the page size didn't work properly with devices
    with rotated coordinate systems.
    	- If an error occurred, and the error object wasn't the last
    element of its procedure, the interpreter would re-execute the error
    object after running the error handler.
    	- Memory devices didn't get resized if HWSize was changed,
    leading to out-of-bounds memory accesses.

    Moves revision and revisiondate from gs_init.ps to iinit.c.  Adds a
    -v switch that just prints these out.

    Arranges things so that if Ghostscript is reading from a pipe (`-'
    switch on the command line) and encounters an error, it exits with
    status 1 rather than 0.

    Changes the interpreter interface so the caller explicitly passes a
    pointer for storing an error object.

### Library

    Fixes bugs:
    	- The automatic adjustment of the scaling for variant paper
    sizes caused the image to get expanded when it should have been
    contracted, and vice versa.
    	- The curve flattener insisted that each line segment be no
    more than 2 x the flatness in length, leading to an enormous number
    of segments even when not necessary for accuracy.
    	- flattenpath and strokepath discarded a trailing moveto.
    	- strokepath treated "0-width" lines as really having a width
    of zero, rather than one pixel.
    	- Buffered devices weren't closed and reopened if the amount
    of buffer space was changed.
    	- stroke used the line cap at the beginning of each subpath
    even if the subpath was closed.

    Removes the requirement that the clipping rectangle fall in the
    non-negative quadrant of device space.  (This was causing problems
    for Ghostview, but removing it required adding the extra clipping
    step to the drawing routines in the drivers.)

## Version 2.5 (8/18/92)

This version adds Type 1 hinting, CCITTFax encoding and decoding, and Microsoft Windows support, as well as the usual minor improvements and bug fixes.

### Procedures

    Fixes bugs:
    	- GSIMPATH, SLZWD, and SLZWE were omitted from the VMS
    makefiles, and GSIM2OUT was not removed.
    	- landscap.ps messed up the current path.

    Adds new switches:
    	-dSAFER disables file writing and directory modification.
    	-dESTACKPRINT causes errors to print the execution stack with
    == instead of =.
    	-sOutputFile=<string> replaces -sOUTPUTFILE (which is still
    recognized) for setting the output file or pipe for the default
    (printer) device.
    	-sPAPERSIZE=<sizename> initializes the paper size.
    	-dBufferSpace=<number> sets the buffer size for the default
    (printer) device.

    For Unix systems, changes the directories in GS_LIB_DEFAULT from
    `pwd` to $(gsdatadir), i.e., normally $(datadir)/ghostscript, where
    datadir is normally /usr/local/lib.

    Adds a note in the header file to the effect that the X Windows
    driver expects to find header files in $(XINCLUDE)/X11, not in
    $(XINCLUDE).

    Changes -q so it defines QUIET as true instead of null (so it can be
    used in the middle of the command line as well as at the beginning).

    Renames the history.doc file as NEWS.

### Utilities

### Platforms

    Fixes bugs:
    	- The stack size was not getting increased on the Watcom
    platform.

    Removes "b" from the scratch file opening modes in gp_unix.c and
    (conditionally) in gdevprn.c, to pacify the DECstation Ultrix system.

    Adds a makefile (bcwin.mak) and a platform file (gp_mswin.c) for
    Microsoft Windows.

    On MS-DOS platforms (including Windows), uses the TEMP environment
    variable to designate the directory for scratch files.

    Changes std.h so that the VMS C compiler uses function prototypes and
    'const'.

    Changes the VMS cc makefile so it doesn't use ansi2knr.

### Fonts

    Fixes bugs:
    	- findfont left an extra entry on the stack if it couldn't
    find the default font.

    Renames bchi, ncri, and puti as bchri, ncrri, and putri, to conform
    with the naming scheme for other fonts.

    Adds $(CCFLAGS) to the command line used for compiling fonts.

    Converts the .pfa fonts (CharterBT, IBM Courier, and Utopia) to .gsf,
    by removing eexec encryption and also removing some mysterious
    unmapped characters from Courier.  This makes these fonts work with
    DISKFONTS.

    Changes the implementation of compiled fonts so they are read-only
    and sharable (no external references).  (They are, however, not
    position-independent.)

    Provides a way to use compiled fonts on platforms that limit the
    number of characters in an identifier.

    Adds public-domain Cyrillic and Cyrillic-Italic fonts.

    Adds a 'userdict begin' to .loadfont, because Type 3 fonts produced
    by Fontographer expect a writable dictionary on the top of the stack.

    Changes definefont for Type 1 fonts to insert UnderlinePosition and
    UnderlineThickness entries in FontInfo if they are absent, because
    many word processors incorrectly assume these entries are present.

### Drivers

    Fixes bugs:
    	- The documentation in use.doc said that the densities for
    9-pin Epson printers were 60x60 to 240x60, rather than 60x72 to
    240x72.
    	- gdevprn.c smashed one byte beyond the end of the string
    given as the OutputFile device property.
    	- The X11 driver used XVisualIDFromVisual, which is not
    defined in X11R3.
    	- The SunView driver modified the input data, which was
    declared as const.
    	- The LaserJet IIP and III drivers shifted the page 185
    pixels to the left and 0.25" down, because the initialization string
    was incorrect.
    	- The PCX driver wrote 16-bit values using the byte ordering
    of the platform, rather than always LSB first.
    	- For vertical spacing, the LaserJet and DeskJet drivers used
    a command that spaces N/300", rather than N scan lines, but gave it a
    parameter in scan lines.
    	- The VESA driver didn't allocate a full 256-byte buffer for
    reading the mode information from the BIOS, causing the stack to get
    smashed by newer VESA implementations.
    	- The VESA driver didn't use the scan line length returned by
    the BIOS, causing garbage output for some cards and some resolutions.
    	- The generic printer driver didn't free the bitmap when
    closing the device, if it fit entirely in memory.
    	- The PaintJet driver allocated its data areas on the stack
    instead of with gs_malloc.
    	- The generic printer driver didn't attempt to increase the
    buffer size if it was too small.
    	- The band list driver didn't split large bitmaps properly,
    leading to garbled characters at high resolutions.
    	- The GIF and PCX drivers used a color map that often turned
    gray colors into non-grays.

    Changes the default put_props procedure so that if the device is
    open, setting HWSize and/or HWResolution closes the device and
    reopens it.

    Adds a driver for Microsoft Windows 3.n.

    Updates the 'cdj' and 'dj500c' DeskJet 500C drivers with new versions.
    (This are user-contributed drivers.)

    Changes gdev_prn_put_props so OutputFile can be changed dynamically.

    Updates the DEC LN03 driver to also handle the LA50 and LA75.  (This
    is a user-contributed driver with a FSF copyright.)

    Changes the LaserJet/DeskJet driver so that -DA4 in the makefile
    makes A4 paper the default.  The driver now also sends an appropriate
    page size selection command to the printer if the printer supports it.

    Changes all the Aladdin-supported drivers to return appropriate error
    codes rather than -1.

    Adds a driver for the S3 86C911, a PC graphics accelerator used in
    the popular Diamond Stealth board.  This is the first driver that
    uploads character bitmaps to a device; others will probably follow.

    Adds user-supplied code to the Epson driver so it will do triple
    passes on 9-pin printers for higher resolution.

    Adds user-supplied code for the PaintJet XL to the PaintJet driver.

### Interpreter

    Fixes bugs:
    	- zdps1.c didn't include alloc.h.
    	- On 32-bit systems, if maxlength of a dictionary was less
    than the actual allocated space, length could become larger than
    maxlength.
    	- flushfile didn't actually flush data when reading.
    	- The ASCII85Decode filter signalled EOF prematurely.
    	- The scanner interpreted .3D.glorp as the number 0.3, rather
    than as a name.
    	- Closing a file freed the stream structure, creating
    dangling references if there were other file objects pointing to the
    same stream.
    	- eexec called handleerror if an error occurred, instead of
    letting the error propagate to an enclosing stopped.
    	- gs.h made perror illegal, instead of defining it in terms
    of strerror.
    	- One-character names weren't being allocated at
    initialization, so they could be left dangling after a restore.
    	- Internal gsaves (i.e., the ones in show and setcachedevice)
    didn't also save istate, so setfont inside a BuildChar procedure
    might cause the font outside to get changed.
    	- The allocator incorrectly freed objects in the current
    chunk that were older than the current save.
    	- mark was just an object, rather than an operator, so 'bind'
    didn't bind it.  (This is theoretically a problem for null, true, and
    false also, but even more unlikely to be a problem in practice.)
    	- packed_get didn't cast packed integers to int, so negative
    integer elements of packed arrays came out wrong.
    	- quit just did a gs_exit, instead of returning to the driver
    in an orderly way.
    	- Because check_type_access checked for errors in the wrong
    order, sometimes type errors were reported as access errors.
    	- eq didn't check for stack underflow.
    	- Some of the stream_procs structures weren't properly
    declared const, leading to link errors on VMS.

    Implements currentcolor, currentcolorspace, setcolor, and
    setcolorspace (for DeviceGray, DeviceRGB, and DeviceCMYK only).

    Implements the dictionary form of image and imagemask.  All the pairs
    in the Decode array must be the same; Interpolate is ignored.  The
    only supported color spaces are DeviceGray, DeviceRGB, and
    DeviceCMYK.

    Implements files as allowable sources for the image operators.

    Removes the index field from the name structure, moving it to the
    'size' field of name refs.

    Changes the unread/sungetc operation to require that the character be
    the same as the last one read from the file.

    Adds fflush calls to some debugging printout routines, because Unix
    sometimes buffers terminal output.

    Implements the CCITTFaxEncode and CCITTFaxDecode filters.  Implements
    the general case of the SubFileDecode filter.

    Changes definefont to treat a UniqueID of 0 as equivalent to no
    UniqueID, because Fontographer output apparently often violates the
    specification in this way.

    Changes the default printer screen from 32.5 to 46 cells/inch.  (The
    old value was appropriate for a hand-rotated cell with two spots in
    it.)

    Changes the utility routines to allow an integral real wherever an
    integer parameter is expected in a dictionary, because Fontographer
    produces fonts that violate the Adobe specification in this way.

    Adds a `dosio' feature that provides direct access to memory and to
    I/O ports under MS-DOS.  (This feature is not included in the
    standard executables, of course.)

    Changes the default character cache limit to a 1/4" x 1/4" character
    at the default resolution, rather than basing it on the preallocated
    cache size.

    Removes support for t_color objects, which haven't actually been used
    for several releases.

    Implements setcmykcolor and currentcmykcolor as operators, so they
    will interact properly with setcolorspace and currentcolorspace.

    Changes the name of the file.h header file to files.h, to work around
    a bug in the VMS header library.

    Adds command line switches @file (to treat file as more command line,
    to get around the DOS 128-character command line limit) and -ffile
    (so one can specify file names that begin with - or @).

    Changes the PFBDecode filter so it takes an additional boolean that
    says whether or not to convert binary packets to hex.  (Conversion to
    hex and back to binary accounted for a substantial amount of the time
    required to load .PFB fonts.)

    Splits off `copydevice' as a separate operator again.

### Library

    Fixes bugs:
    	- In the VMS environment, string_.h used its own prototypes
    for the str... and mem... functions instead of <string.h>
    	- gx_alloc_char_bits declared cdsize as long, but didn't
    shorten it when passing it to shorten_cached_char.
    	- Stroking didn't suppress fattening of the lines.
    	- kshow didn't update the cached CTM information in the show
    enumerator when returning from the callout, so further characters
    could get drawn in the wrong place.
    	- When a memory device returned its initial matrix, it
    smashed the padding fields, which contained the interpreter's type
    information.
    	- setcachedevice didn't set the initial matrix in the cache
    memory device.
    	- image_set_rgb (in the image operators) didn't do a
    gx_color_from_rgb, so in principle one could sometimes get incorrect
    colors in an image.
    	- The decision about whether or not to cache a character
    bitmap incorrectly compared the character size against cmax rather
    than cdata_size.
    	- show didn't reset the in_cachedevice flag in the graphics
    state, so characters rendered by a recursive show were never cached.
    	- clip and eoclip didn't release the intermediate flattened
    clip path, causing memory to be lost.
    	- The tile_diff routine didn't handle the case of two
    identical tiles properly; this produced garbage in the band list
    file.
    	- stringwidth didn't round the character origin to an
    integral pixel; this interacted badly with hinting, causing
    improperly hinted characters to wind up in the cache.
    	- Bitmaps (including characters) were displaced, as well as
    being clipped, if they intersected the top of a clipping region.
    	- In gxclist and gdevmem1, the raster computation (although
    not the result) could overflow an int on 16-bit machines.

    Implements decoding (sample mapping) for image and imagemask.

    Implements hinting for Type 1 fonts, based on (but not copying) the
    algorithms from the X11R5 tape.

    Changes curve rasterizing to use sampling, rather than recursive
    subdivision, for characters.  This produces noticeably better output.
    Speed penalty for non-cached characters is less than 10% at display
    resolutions, up to 50% for 300 dpi printers.

    Implements gs_setcmykcolor and gs_currentcmykcolor.  These are
    semi-fake, since they simply convert the color to and from RGB, but
    the former does set the current color space properly.

    Changes clipping regions so they use the any-part-of-pixel rule
    rather than the center-of-pixel rule.  This helps avoid dropouts when
    using very small regions.

    Implements stroke adjustment.

## Version 2.4.2 (5/8/92)

This is another quick release. It finally fixes rotated halftone screens, and cleans up a few minor problems from 2.4.1.

This release is being distributed only to beta testers and commercial licensees, since I don't want to be distracted from working on 2.5.

### Procedures

    Fixes bugs:
    	- UTRACE still appeared in the VMS makefiles.
    	- The support files (*.bat, *.doc, *.gsf, *.ps, Fontmap,
    COPYING, README) weren't included in the MS-DOS tar file.
    	- The Unix install script didn't install landscap.ps.

    Replaces the type1imagepath operator with PostScript code (impath.ps,
    type1ops.ps) based on the new .imagepath operator.

    Renames LICENSE as COPYING.

### Utilities

    Fixes bugs:
    	- pcharstr.ps had an occurrence of Subrs rather than /Subrs,
    causing it to not print the Subrs, or to get an error if there were
    none.
    	- font2c.ps didn't get the const declarations for string
    dictionaries quite right.
    	- The missing newline at the end of gsbj.bat confused GNU
    diff.
    	- ansi2knr would go into an infinite loop if a statement
    exceeded its internal buffer size.
    	- Compiled fonts would get processed by ansi2knr, which
    messed them up.

### Platforms

    Fixes bugs:
    	- Ghostscript didn't supply equivalents for rename and
    gettimeofday, which some System V platforms lack.
    	- The missing newline at the end of gp_dosfb.c confused GNU
    diff.

    Changes the Borland makefiles so that stack checking is only enabled
    if DEBUG or TDEBUG is set.

### Fonts

    Changes the names of the Utopia fonts from utrg/utb/utbi/uti to
    putr/putb/putbi/puti, for consistency with the rest of the font names.
    Changes cour/courb/courbi/couri to ncrr/ncrb/ncrbi/ncri likewise.

    Replaces the Charter fonts with the CharterBT fonts donated by
    Bitstream to the X11R5 distribution.

    Adds font aliasing capability to Fontmap.  Replaces
    Courier-[Bold]Oblique and ZapfChancery-MediumItalic by aliases.

    Changes the FontBBox of the Hershey fonts to be an executable, rather
    than a literal, array.

### Drivers

    Fixes bugs:
    	- The GIF driver omitted a `private' on the definition of
    gif_print_page.
    	- The GIF driver wrote 16-bit values using the byte ordering
    of the platform, rather than always LSB first.
    	- George Cameron's DeskJet 500C driver had an incorrect
    control sequence for skipping blank lines.

    Adds 'const' in many places, including the tile and bitmap arguments
    of the tile_rectangle, copy_mono, and copy_color driver routines.
    THIS IS A DRIVER INTERFACE CHANGE.  (Printer drivers are not
    affected, since they don't implement these routines.)

    Adds a driver for the Trident TVGA.

### Interpreter

    Fixes bugs:
    	- alloc_free sometimes incorrectly chose to put an unaligned
    block in an old segment on a freelist.
    	- The default undercolor removal function returned its
    argument rather than returning 0.

    Adds NullEncode and SubFileDecode to the standard filters, since
    bdftops uses the latter.

    Adds RunLengthEncode and RunLengthDecode to the optional filters.

    Removes the type1imagepath operator.  (It is still available as
    PostScript code, impath.ps.)  Replaces it with a simpler outline
    tracing operator .imagepath.

    Adds 'const' in many places.

    Makes fileposition (but not setfileposition) legal for NullEncode
    filters.

    Changes the default transfer function for high-resolution devices
    from the identity function to the square root function.

    Moves array_get from zgeneric.c to iutil.c.

    Changes uses of fopen to add a "b" to the access mode, rather than
    relying on the _fmode global variable on MS-DOS platforms.

    Allows use of the -Z switch even when gsmain.c wasn't compiled with
    -DDEBUG, since other modules might have been.

    Reorganizes gs.c and gsmain.c so that the latter can be used in
    server environments.

    Replaces all uses of stdin/out/err with gs_stdin/out/err.

    Makes the number of permanent entries on the dictionary stack a
    parameter, to allow inserting globaldict in the future.

    Changes BlueShift in the Type 1 font Private dictionary to allow real
    numbers.  (This differs from the Adobe specification, but at least
    one commercial font has a real number for BlueShift.)

### Library

    Fixes bugs:
    	- The doubling check in init_ht (gxht.c) still sometimes
    thought there was enough room to double the tile when there actually
    wasn't.
    	- Rotated halftone screens didn't work.
    	- gxarith.h used #ifdef vax, rather than #if
    !arch_floats_are_IEEE, to test whether IEEE floats were being used.
    	- pathforall didn't report a trailing moveto.

    Replaces gs_type1imagepath with gs_imagepath.

    Allows sOUTPUTFILE=-, meaning output to stdout.

    Adds 'const' in many places.

    Replaces all uses of stdin/out/err with gs_stdin/out/err.

## Version 2.4.1 (4/21/92)

This is a quick release to fix minor problems discovered in 2.4, and to add a few improvements that didn't quite make it into 2.4. It also adds GIF and PCX file support.

### Procedures

    Fixes bugs:
    	- Some makefile dependencies, and the ccgs script, caused trouble
    for parallel versions of `make'.
    	- Compiling genarch with -O with gcc on the RS/6000 produced a
    buggy executable.

    Fixes some minor problems in make.doc.

    Adds DEVICE_DEVS2..5 to handle long device lists.

    Removes the need to set GS_RUN_EXE when using the Watcom compiler on
    MS-DOS systems.

    Gets rid of gs_ccfnt.ps, merging its function into gs_fonts.ps.

    Gets rid of gconfig.ps; this information is now compiled in gconfig.c.

### Utilities

    Fixes bugs:
    	- The palette for pstoppm in 8-bit mode didn't contain all 8
    primary colors.
    	- font2c used just values_ to mean &values_[0]; some compilers
    couldn't handle this.

    Makes font2c insert `const' in many appropriate places.

### Drivers

    Fixes bugs:
    	- The SunView driver had not been updated properly for 2.4 and was
    pretty thoroughly broken.
    	- None of the printer drivers worked properly with the Watcom
    compiler, because stdprn was doing \n -> \r\n substitution.
    	- If the generic printer driver couldn't allocate the requested
    size command list buffer, it gave up rather than trying to allocate a
    smaller buffer.
    	- The SuperVGA drivers (except for the VESA driver) didn't
    work with the Watcom compiler, because a couple of places in the
    drivers weren't truncating the offset of "segmented" pointers
    properly.
    	- Some of the H-P used <esc>*b#Y rather than <esc>*p+#Y for
    vertical positioning; this apparently is wrong, at least for the
    LJIIp.

    Removes the dependence of the X Windows driver on Xt, Xext, and Xmu.  As a
    result, Ghostscript will not install a standard colormap itself, but it
    will use one if one is already installed.

    Adds a set of drivers for Portable Bitmap, Graymap, and Pixmap file
    formats.

    Adds drivers for monochrome, EGA/VGA-style, and SuperVGA-style PCX
    file formats.

    Adds drivers for monochrome and 256-color GIF file formats.

### Fonts

    Adds ZapfChancery-MediumItalic as a copy of ZapfChancery-Oblique.

### Interpreter

    Fixes bugs:
    	- A value with l_new set could 'escape' to save level 0 on a
    stack; if stored, it prevented the slot from being saved and restored
    properly.
    	- 16#7fffffff + 1 gave the floating point equivalent of -2^31, not
    2^31.
    	- The PFBDecode filter computed the packet length incorrectly if
    the 0x8000-bit of the length was set.
    	- 5-byte numbers in Type 1 CharStrings complained of a rangecheck
    if they exceeded 16 bits, rather than if they exceeded the integer part of
    a fixed.
    	- (, ), and \ appearing in file name arguments in the command
    line did not work properly.

    Adds 'const' in many places.

    Changes the random number generator to be the same as the one used in
    Level 2 PostScript (as reported by Ed Taft on comp.lang.postscript).

    Exits with code 1 rather than code 0 on an unrecoverable error detected at
    the PostScript level.

    Makes dictionaries expand automatically when they fill up.

    Adds gp_exit to complement gp_init.

    Changes dictionaries to always allocate a power of 2 entries on
    32-bit machines.  Changes the name table to allocate indices
    scattered, so dictionary lookup doesn't have to do a multiply to
    scramble the index.

    Changes the handling of currentfile to do "shallow binding" so stack
    searching is almost never required.

### Library

    Fixes bugs:
    	- arc and arcn got a numeric exception if the radius was zero.
    	- The undocumented 15 opcode in Type 1 fonts wasn't ignored.
    	- PaintType 3 wasn't allowed.  (It isn't clear what it should
    mean; we treat it as equivalent to 0.)
    	- The VAX/VMS C compiler was generating incorrect code for the
    chi_bits and cmask macros in gdevmem, producing incorrect output.
    	- If the result of the slow algorithm for intersecting clipping
    paths was a rectangle, the wrong thing happened (cbox didn't get set).
    	- gx_path_is_rectangle didn't recognize open rectangles.
    	- clist_change_tile didn't check properly whether the tile
    size had changed, so changing the screen could produce invalid band
    files.
    	- The image operators did the wrong thing in the 1-for-1
    case, interleaving N bytes of data with 7*N bytes of garbage.
    	- stroke sometimes handled bevel and miter joins wrong in
    reflected coordinate systems.
    	- init_ht checked incorrectly whether there was enough room
    to Y-replicate tiles, so sometimes it did it when it shouldn't have.
    	- stroke sometimes thought lines were thin when they weren't.

    Adds 'const' in many places.

    Adds support for 2- and 4-bit-per-pixel memory devices.

## Version 2.4 (3/25/92)

This is a major release that adds SuperVGA support, support for Metrics, settable device properties, and incremental font loading. It also includes important performance improvements, based on rewrites of some key algorithms, and quite a few new Level 2 / Display PostScript facilities.

### Procedures

    Fixes bugs:
    	- The rule for compiling gconfig.c didn't include the -I switches.
    	- .bat files were being distributed with a \n line terminator
    rather than \r\n.
    	- A CLOSE MODULE_LIST was needed after END_COMPILE: in the VMS
    command files.
    	- Unix systems couldn't handle multiple drivers with overlapping
    sets of files.
    	- -s<name> defined <name> as a null, rather than as an empty string.

    Adds gconfig.ps to the list of needed configuration files.

    Changes the way that the makefile handles nested .h files, so that it
    doesn't have to `touch' them.

    Adds the loadallfonts procedure to gs_fonts.ps.

    Changes the standard DOS configuration to include VGA, EGA, VESA, Epson,
    BubbleJet, and H-P printer drivers.

    Renames ghost.mak as gs.mak, and gdevs.mak as devs.mak.

    Adds a USE_ASM flag so that one can build a DOS version of Ghostscript
    without having an assembler.

    Splits off common code from the two MS-DOS makefiles into tccommon.mak.

    Replaces the COPYING and LICENSE files with a new LICENSE file containing
    version 2 of the GNU General Public License.

    Removes DEVICES and DEVICE_OBJS from the makefiles, since they are no
    longer needed.

    Adds a GS_DEVICE environment variable to supply a default device name if
    desired.

    Adds ansihead.mak and unix-ansi.mak, to parallel [g]cc-head.mak and
    unix-[g]cc.mak, for other ANSI C compilers.

    Changes the way that optional features are defined in the makefiles, so
    that they actually work.

    Adds support for the Watcom C/386 compiler.

    Allows # in the command line as equivalent to =, to compensate for
    brain-damaged MS-DOS shell.

    Adds -sOUTPUTFILE= to set the output file or pipe.

    Adds -dWRITESYSTEMDICT to leave systemdict writable.

### Utilities

    Fixes bugs:
    	- pcharstr.ps insisted on having Subrs be present in the font.
    	- pcharstr.ps decoded negative numbers between -108 and -1131
    incorrectly.
    	- pfbtogs.ps didn't handle packets longer than 64K correctly.

    Changes the bdftops utility so that it makes entries for UnderlinePosition
    and UnderlineThickness in FontInfo, and so that it always records a
    FullName (the FontName if no other is provided).

    Changes the name of the pfbtops utility to pfbtogs, because groff already
    includes a program called pfbtops.

    Adds the gslp utility for doing "line printing" of text files, similar to
    enscript + lpr.

    Adds a new variable DITHERPPI that enables a different dither pattern,
    claimed to be better for printers.

    Adds the font2c utility for compiling Type 1 fonts into C, so they can be
    linked into an executable rather than loaded dynamically.

### Drivers

    Fixes bugs:
    	- gdev_prn_copy_scan_lines was erroneously masking the last byte
    of data even on color printers, as was paintjet_print_page.
    	- The TruFax driver had a couple of compilation errors, since it
    hadn't been compiled in a while.
    	- The BGI driver sometimes didn't consult BGIPATH when looking for
    .BGI files.
    	- initclip did the wrong thing with memory devices.
    	- The BGI driver didn't look in BGIDIR for .BGI files.
    	- The Epson driver didn't set the right margin properly with
    ESC+Q.
    	- The BJ-10e driver was badly broken.
    	- gdev_prn_open/close_printer didn't reset the command list file,
    so it was taking quadratic time to print multi-page documents.

    Adds color to the SunView driver.

    Adds selectable resolution (75, 100, 150, or 300 DPI) to the
    DeskJet/LaserJet driver.

    Changes gssetdev so that drivers can specify special libraries to be
    loaded, as well as object files.

    Adds a driver for VESA-compliant SuperVGA displays.  This driver handles
    all resolutions from 640 x 400 up to 1280 x 1024, in 256-color mode.  The
    default is VGA resolution (640 x 480).

    Adds a driver for the ATI Wonder SuperVGA card, and for SuperVGA cards
    using the Tseng Labs ET3000 or ET4000 chip such as the STB VGA EM-16 and
    the Orchid ProDesigner II (256-color modes only).

    Adds a driver for Trident and Tseng Labs SuperVGA cards in 800 x 600,
    16-color modes (for cards with only 256K of memory).

    Adds user-contributed drivers for the Ricoh 4081, DEC LN03, Canon LBP-8II,
    and H-P DeskJet 500C printers.

    Adds Tim Theisen's Ghostview changes to the X11 driver.

    MAKES NON-BACKWARD-COMPATIBLE CHANGES TO THE DRIVER PROCEDURE INTERFACE as
    follows:

    	- Changes map_rgb_color and map_color_rgb to always work in a
    	    16-bit color value space, rather than a space defined by the
    	    maximum number of distinct colors provided by the device.

    	- Adds an argument to the output_page procedure to indicate
    	    whether the procedure is being called for copypage or
    	    showpage, and a num_copies argument.

    	- Adds a gx_bitmap_id to the copy_ and tile_ procedures, so that
    	    drivers can cache bitmaps in the server or device if they want
    	    to.

    	- Removes fill_trapezoid and tile_trapezoid.

    	- Adds a new get_bits procedure for reading the bits back from the
    	    driver buffer (when possible), replacing copy_scan_lines.
    	    This procedure takes a new argument describing padding and
    	    byte swapping, and returns a different value from
    	    copy_scan_lines.

    	- Adds get_props and put_props procedures for accessing arbitrary
    	    additional properties of devices.  The interface is quite
    	    complex, but provides a great deal of flexibility.

    See drivers.doc for details.

    Changes gdev_mem_bytes_per_scan_line to gdev_prn_bytes_per_scan_line.

    Adds a user-contributed driver for DigiBoard, Inc.'s fax software.

### Fonts

    Changes Type1BuildChar so it uses the information from the Metrics
    dictionary in the font, if Metrics is present.

    Changes findfont (.loadfont) so it recognizes .PFB fonts and can load them
    directly.  Also changes .loadfont to disable packing temporarily, because
    some fonts rely on procedures being writable (!).

### Interpreter

    Fixes bugs:
    	- The hypot function is not available on some Unix systems.
    	- Ghostscript didn't flush and close files when exiting.
    	- In statusdict, the /margins procedure used .leftmargin, but
    /setmargins used .lmargin.
    	- An out-of-range putinterval would simply do nothing, rather than
    reporting an error.
    	- If an attempt to allocate a block larger than the allocator's
    chunk size (20K) failed, the allocator would erroneously think it had
    succeeded.
    	- The bind operator made the top-level procedure read-only, as
    well as interior procedures.
    	- gs.c copied 1 extra character for the value of strings defined
    on the command line with -s...=, which could smash the first byte of the
    next object in memory.
    	- copying a dictionary erroneously required the maxlength of the
    destination to be greater than or equal to the maxlength of the source,
    rather than the length of the source.
    	- undef didn't correctly decide when to mark a deleted entry as
    deleted vs. free; as a result, some keys couldn't be looked up properly
    after an undef.
    	- type1encrypt and type1decrypt didn't set the size of the result
    properly.
    	- cvi and cvr didn't allow leading or trailing whitespace in
    strings.
    	- cvs didn't cause an error if the destination string was too
    short.
    	- Many operators didn't check correctly for stack underflow (off
    by 1).
    	- `for' used reals, rather than integers, if the limit was a real,
    even if the initial value and increment were integers.
    	- `restore' didn't properly invalidate copies of the save object
    being restored from; `save dup restore restore' would crash.
    	- `restore' sometimes didn't undo stores into matrices that were
    stored into by operators.  (The identity matrix always had l_new set.)
    	- readline gave a rangecheck if the input line exactly filled the
    string.
    	- `--' as the last switch on the command line caused a crash
    rather than an error message.
    	- On MS-DOS systems, filenameforall didn't handle patterns with a
    drive or directory specifier properly.
    	- stroke sometimes called gz_draw_line_fixed even if the line went
    outside the clipping box by 1 pixel.

    Changes the loop that binds procedure "operators" to entirely disable the
    handling of the typecheck error, rather than to use stopped.  This cuts
    initialization time significantly, and also eliminates about 35K of wasted
    space (for saving the stacks).

    Changes the version "operator" so it returns 47.0.  Adds "revision" to
    define the Ghostscript version # x 100.

    Adds gscurrentresolution and gssetresolution procedures for getting and
    setting the device resolution.

    Adds -r<res> and -r<xres>x<yres> as command line options for setting
    device resolution.

    Adds a facility for incrementally loading the individual CharStrings of a
    Ghostscript font from the disk.  This can save a lot of memory, at the
    expense of slower rendering.  (It is intended primarily for MS-DOS
    systems.)

    Changes findlibfile to return the name of the file that was actually
    opened, as well as the file itself, when the operation succeeds.

    Changes the name of the main entry to the interpreter from interpret to
    gs_interpret, because of a conflict with a Data General library procedure.

    Adds the .setmetrics operator to set the metrics for the current
    character for Type 1 fonts.

    Adds more LaserWriter-specific entries to statusdict.

    Gives names to all the internal `operators', so they will print out
    reasonably when an error occurs.

    Extends the status operator to accept a string and return file
    information, as defined for Level 2 PostScript.

    Adds the filter operator and some specific filters: ASCII85Encode,
    ASCII85Decode, ASCIIHexEncode, ASCIIHexDecode, eexecDecode, NullEncode,
    PFBDecode, and the null case of SubFileDecode.

    Extends the scanner to recognize the Level 2 << and >> tokens.

    Adds a facility for extracting the text strings from a PostScript file and
    writing them out in a simple format (selected by -dASCIIOUT, implemented
    by gs_2asc.ps).

    Implements all of the remaining Display PostScript facilities that are
    also in Level 2 (i.e., everything in section A.1.3 of the PostScript
    Language Reference Manual, Second Edition, that is not also in section
    A.1.2).  The virtual memory operations are all stubs; the new halftone
    options are not fully implemented.

    Changes makeimagedevice to use a string of gray or RGB values, rather than
    an array of color objects, to specify the palette.  Removes
    currentgscolor and setgscolor from the interpreter, but leaves t_color
    objects in, since they may be useful later.

    Adds getdeviceprops and putdeviceprops for manipulating device properties.
    Currently defined properties for all devices: InitialMatrix, HWResolution,
    HWSize, Name.  Currently defined properties for printers: BufferSpace,
    MaxBitmap, OutputFile.  OutputFile allows |command for piping on Unix
    systems.

    Removes deviceparams and makedevice.  Adds devicedefaultmatrix.

    Implements reversepath.

    Makes copy work on devices.

    MS-DOS specific
    - - - - - - - -

    Fixes bugs:
    	- iutilasm.asm wouldn't assemble with newer versions of MASM if
    CPU_TYPE was set to 286 or above.
    	- CPU_TYPE=386 didn't properly substitute the faster
    multiply/divide routines under Turbo C++ or Borland C++, only under the
    original Turbo C.

### Library

    Fixes bugs:
    	- A curve whose first and last points were the same wouldn't get
    drawn at all.
    	- A bug in the Turbo C++ compiler generated bad code when shifting
    a long right by 1 bit.
    	- If stroking a dashed line ever encountered a segment that was
    completely blank, Ghostscript would indirect through a null pointer.
    	- arc and arcn gave an error if the radius was negative.
    	- stroke always used the general algorithm, even if the line was
    guaranteed to be thin.
    	- arc and arcn erroneously reduced the angles mod 360.
    	- Very large or negative 32-bit numbers in Type 1 fonts didn't
    work properly on MS-DOS systems (the ff0000 bits got set to zero).
    	- Color printer devices rendering entirely in memory only
    allocated a monochrome-sized bitmap.
    	- clip and eoclip didn't intersect the paths properly in the
    general case.
    	- charpath erroneously rounded the current point to an integral
    value, causing characters to be spaced improperly.
    	- The definition of max_color_param got some compilers confused.
    	- charpath always used quadratic time and space, and dropped all
    but the last character when used with a Type 3 font.
    	- Stroking a path with a 180 degree angle would incorrectly miter
    instead of beveling.
    	- Type 1 fonts used the current flatness for curves, which could
    produce bad (and inconsistent) results.
    	- Stroking a degenerate line segment produced incorrect results.

    Changes the character cache to use the UniqueID as the key, when
    available, instead of the font pointer.  This dramatically improves
    performance when fonts are getting removed and reloaded because of page
    isolation with save/restore.

    Removes some unnecessary casts to (float) from gsmatrix.c and gscoord.c.

    Changes the Type 1 interpreter so that it rounds line and curve endpoints
    to the center of the nearest half-pixel, and omits null line segments.
    This both speeds up rendering at small sizes and improves output quality.

    Changes gs_deviceparams to return resolution as well as extent; changes
    gs_makedevice to accept resolution as well as extent.

    Replaces the algorithm for approximating circular arcs with curves with a
    more accurate one.

    Changes gs_point and gs_rect to use doubles rather than floats.

    Adds gs_setmetrics, for overriding Type 1 font metrics for the current
    character.

    Changes clipping to use lists of rectangles rather than path intersection.
     This makes a big difference when clipping bitmaps (including characters).

    Changes the character cache to discard entries incrementally, rather than
    clearing the entire cache when it fills up.

    Changes the implementation of transfer functions to use a cached map,
    built when the transfer function is set.  This makes transfer functions
    work properly in all situations, including images.

    Defines a .quit operator that takes an exit code, and redefines quit in
    terms of it.

    Adds support for 16-bit-per-pixel devices in gdevmem.

    Adds gs_copydevice and gs_deviceinitialmatrix; removes gs_deviceparams and
    gs_makedevice.

    Changes setscreen to ensure that the cell is always at least 4x4 pixels in
    size.

## Version 2.3 (8/28/91)

This is a minor release to fix two bugs and add the PaintJet driver, which didn't make it into 2.2.

### Utilities

    Changes the pstoppm utility so it counts pages correctly even in the
    presence of arbitrary saves and restores.

### Drivers

    Adds a new, "supported" PaintJet driver.

    Changes the Epson driver to use ESC+D rather than ESC+\ for horizontal
    positioning, since many printers don't support the latter.

    Adds horizontal double-density (two-pass) printing to the Epson driver, so
    it can do 240 x 60 and 360 x 180 densities.  (Vertical double density is
    not supported yet.)

## Version 2.2 (6/1/91)

The purpose of this release is to add save/restore, and a few miscellaneous Level 2 P*stScr*pt features such as undef. It also includes major improvements in graphics quality and in handling of high-resolution printers.

### Procedures

    Changes the version numbering to M.mpp rather than M.m.p, so that
    `version' can be a real number for those programs that insist on it.

    Renames ghost.ps as gs_init.ps, gfonts.ps as gs_fonts.ps, and statusd.ps
    as gs_statd.ps.  The initialization files now all are named gs_*.ps.

    Renames gdevs.{c,h,tl} as gconfig.{c,h,tl}.

    Changes the relevant makefiles and command files so that a single build
    can contain several drivers that share code, e.g., the Epson driver and
    the DeskJet driver.

    Changes gs_init.ps so it relies on an external gconfig.ps file rather than
    making a specific test for the presence of Level 2 features.

    Adds an entry for uglyr.gsf to the makefile.

    Removes the distinction between CCA and CCNA, since most of the files now
    contain constructs that require non-ANSI compilation on MS-DOS platforms.

    Adds a `man' page for the ansi2knr utility.

    Changes the documentation (use.doc) to show how to use -sDEVICE=<device>,
    or the selectdevice procedure, to select devices by name.

    Adds DEVICE_DEVS to the makefiles (analogous to DEVICES and DEVICE_OBJS).
    This finally makes the make procedure fully automatic.

    Adds the name of the initialization file (gs_init.ps) as a
    platform-specific makefile parameter, GS_INIT.

    Removes the test program gt.{c,tr} from the fileset, since it is not
    useful to users.

    Moves the Symbol encoding vector to a separate file (symbol_e.ps), from
    which it is loaded when first used.

    Changes the error handler so it can handle errors that occur while reading
    the initialization files.

    Extends ansi2knr so it can handle `void' and `...' in parameter lists.

    Adds quit.ps to the set of installed files.

    MS-DOS-specific changes
    - - - - - - - - - - - -

    Adds the VGA and BGI drivers to the standard MS-DOS configuration, and
    makes VGA the default.

    Adds a `+' and a newline at the end of gs.tr, to avoid problems with file
    transfer programs or editors that add a newline at the end of files.

    Changes the name of msdos.mak to turboc.mak, and creates a new tbcplus.mak
    makefile for use with Turbo C++ and Borland C++.

    Changes the extension of the loader response files from .tl to .tr.

    Changes the default search path from c:/ghost and c:/ghost/fonts to c:/gs
    and c:/gs/fonts.

    Changes the directory separator from `|' back to ';', since it appears
    that DOS can handle a ; in a command line if it is prefixed with \.

    Unix-specific changes
    - - - - - - - - - - -

    Changes the uses of install in unixtail.mak so they only install a single
    file at a time, which is all that the standard Unix install allows.

    Removes the duplicate files (README/readme, LICENSE/license,
    COPYING/copying, Fontmap/fontmap).

    Changes the ld flags from LDPLAT to LDFLAGS.

    Adds XCFLAGS and XLDFLAGS.  These are concatenated with CFLAGS and LDFLAGS
    respectively.  The intention is that they be set from the `make' command
    line if desired.

    VMS-specific changes
    - - - - - - - - - -

    Repairs the omission of ZPACKED from the VMS build lists.

### Drivers

    Fixes bugs:
    	- The SunView driver produced semi-garbage on little-endian
    platforms (Sun-386i) because it didn't swap the bit order.
    	- The X driver would dump core if it couldn't open the display and
    the DISPLAY environment variable wasn't set.
    	- The X driver relied on white = 0, black = ones in a couple of
    places;
    	- The X driver would return an error, instead of clipping, if
    asked to display outside the window.
    	- The X driver would create inappropriately sized windows, because
    it believed the server's report of the screen resolution.

    Adds Fran Taylor's Private Eye driver to gdevs.mak and the fileset (not
    supported by Aladdin Enterprises).

    Adds Neil Ostroff's TruFax driver to gdevs.mak and the fileset (not
    supported by Aladdin Enterprises).

    Makes the scratch file template for the printer drivers a per-platform
    quantity (gp_scratch_file_name_template).  Puts the default scratch files
    for Unix in /usr/tmp rather than /tmp.

    Changes the SunView driver to prevent the Ghostscript window from being
    destroyed (which badly confuses the interpreter).

    Extends the Epson driver to handle a variety of print densities in both X
    and Y, to handle 24-pin as well as 8-pin graphics, and to allow optional
    specification of default density in the makefile (gdevs.mak).

    Refactors the printer drivers so that a single driver handles both DeskJet
    and LaserJet.  Adds LaserJet drivers that use the new compression modes on
    the LJ IId/IIp and LJ III.

    Changes all the printer drivers to use band lists rather than bitmap
    paging as the buffering method.  (The individual drivers need only a
    one-line change to replace mem_copy_scan_lines with
    gdev_prn_copy_scan_lines with a different argument.)

    Adds the halftone phase as additional arguments to tile_rectangle and
    tile_trapezoid.

    Adds an entirely new and much simpler PaintJet driver, using the new band
    list interface.

    Adds margin information to the device structure.  This is currently only
    relevant for printer devices.

    Adds BGIPATH and BGIUSER environment variables, allowing additional
    control of the BGI driver.

    Changes the x/y_pixels_per_inch member of the device structure from int to
    float.

### Fonts

    Patches gs_fonts.ps so definefont will add an isFixedPitch entry to
    FontInfo if there isn't one there.

    Removes the old "type 7 path" encoding code from gs_fonts.ps.

    Changes bdftops so it puts isFixedWidth and ItalicAngle entries in the
    FontInfo dictionary of the fonts it creates, since some P*stScr*pt
    programs rely on this.

    Changes bdftops so it synthesizes as many missing characters as possible
    out of the ones that are there (in particular: synthesizes accents out of
    punctuation marks, and accented characters using seac.)  The results
    aren't all that good, but they're a lot better than having characters
    missing out of the font.

### Utilities

    Adds a pfbtops utility for converting .PFB fonts to standard Ghostscript
    fonts.

    Fixes bugs:
    	- ps2image didn't reset things properly between pages for
    multi-page documents.

### Interpreter

    Makes Ghostscript recognize `-' alone as meaning that it should read from
    standard input as though it were a file.  This allows Ghostscript to
    accept a pipe as input.

    Fixes bugs:
    	- seac in type1addpath used the current font's encoding, not
    StandardEncoding.
    	- type1decryptfile (eexec) didn't recognize binary (as opposed to
    hex) representation.
    	- Mentioning a name whose value was a no-access object caused an
    invalidaccess error.
    	- There was a bogus definition of `run' in zfile.c.
    	- The interpreter didn't handle end-of-file on stdin properly.
    	- Real numbers with an 'e' or 'E' but no decimal point were not
    recognized.
    	- On MS-DOS systems, inside strings, \ followed by a newline was
    not discarded properly.
    	- On MS-DOS systems, the long unsigned divide routine sometimes
    gave incorrect answers.  Among other things, this caused alternate-radix
    numbers sometimes to crash the interpreter.
    	- cvrs didn't do the right thing about reals or negative integers.
    	- .echo.mode was being reset with def instead of store, and was
    defined in systemdict rather than userdict.
    	- setgray and settransfer didn't interact properly.
    	- 16#80000000 was being interpreted as a signed integer (and
    converted to a real) rather than an unsigned one.
    	- atan returned 0 sometimes when it should have returned 180.
    	- currentcmykcolor was defined wrong.

    Removes the filename operator, since no standard Ghostscript code used it,
    and it caused problems with some P*stScr*pt files.

    Implements new operators: filenameforall, selectfont (as a procedure),
    stringmatch, undef.

    Adds new standard procedures: selectdevice.

    For MS-DOS, requires that the operand and execution stacks be located in
    the data segment, and uses short pointers to address them.  This produces
    significantly smaller and faster code.  (These changes are not visible to
    users or library clients.)

    Changes the assignment of attribute bits, and adds new bits for
    save/restore and the garbage collector.  Changes many of the macros in
    store.h to support save/restore.  (These changes are not visible to users
    or library clients.)  Implements save and restore.

    Moves type names from gs_init.ps to ghost.h and ztype.c.

    Moves error names from gs_init.ps to errors.h and iinit.c.

    Introduces gp.h as a documented interface to the platform-specific files.

    Adds the -- switch, which allows Ghostscript programs to take arguments
    from the command line.

    Changes many uses of the name `name' to something else, to avoid upsetting
    the Microsoft C compiler.

    Really implements packed arrays -- they took the same amount of space as
    ordinary arrays in previous versions.

    Changes exitserver in serverdict so that it just clears the stacks.  (This
    isn't the correct fix, but it will do as a workaround.)

    Makes many miscellaneous small changes to pacify various compilers.

    Changes gs_fonts.ps so that when "quiet" mode is selected (-q switch),
    Ghostscript doesn't print anything when loading fonts or when substituting
    for undefined characters.

    Defines the name consisting of just a control-D as a no-op, because some
    P*stScr*pt-generating applications put control-Ds in their output.

    Implements halftone phase (sethalftonephase and currenthalftonephase
    operators).

    Removes the -E switch, since it is no longer useful.

    Changes the -w and -h switches to a single -g (geometry) switch, with
    usage -g<width>x<height>.  Makes the -h switch, and a new -? switch, print
    usage help.

    Implements correct handling of stack overflow errors (makes an array out
    of the contents of the overflowing stack, and resets the stack, before
    invoking the error handler).

    Adds t_oparray (`operators' defined as procedures) and the makeoperator
    operator.  This is so that programs like the Distillery that rely on all
    operators being bound by `bind' will work properly.

    Adds a new NOPAUSE flag to suppress the prompt and pause at copypage and
    showpage.

### Library

    Fixes bugs:
    	- gs_type1_interpret didn't store the encryption state or the skip
    count before returning to let the client handle a seac or an endchar in
    the middle of a seac.
    	- The definition of the Type 1 operator ce_testadd was based on
    wrong information; the operator takes only 2 operands and does something
    unknown.
    	- mem_true24_copy_mono wasn't incrementing the destination pointer
    if the color was transparent, leading to garbled characters.
    	- gx_lookup_fm_pair would sometimes look at one entry beyond the
    end of the cached font/matrix pair area.  (This probably had no practical
    effect.)
    	- gs_type1_interpret didn't save the current point when returning
    to the client for a callothersubr, causing some characters to be rendered
    displaced (such as some of the chess pieces in chess.ps).
    	- gs_setgray, gs_sethsbcolor, gs_setrgbcolor, gs_setflat, and
    gs_setlinewidth gave errors for out-of-range operands rather than forcing
    them into range.
    	- Transfer functions were not actually supported.
    	- The area fill algorithm failed on certain complex paths.
    	- The current point was sometimes defined when a BuildChar
    procedure was called.
    	- Stroking a degenerate line didn't display anything for round
    caps or joins.
    	- If the ends of a curve had exactly the same X coordinate, the
    curve sometimes wouldn't be displayed.
    	- Very thin lines that went outside the clipping region would
    sometimes be displayed as dashed, or not at all.
    	- The translation in a FontMatrix was ignored.
    	- Very wide, shallow lines would color extraneous pixels when
    using bevel or miter joins.
    	- Dashed lines didn't join properly at the beginning of a closed
    path.
    	- 0-degree arcs didn't add the appropriate line (possibly
    degenerate) to the path.
    	- gs_type1_interpret didn't reset the callsubr stack when starting
    the base character of a seac, which caused confusion if the accent's
    endchar fell inside a Subr.
    	- Non-monochrome memory memory devices weren't checking the
    arguments of the drawing procedures properly.
    	- The initial clipping rectangle for memory devices was being
    computed wrong.
    	- Null devices had a semi-infinite clipping rectangle instead of
    an empty one.
    	- gs_setlinewidth was treating negative arguments as zero, instead
    of taking the absolute value.
    	- imagemask with a dithered color used a solid color rather than
    the dithered one.

    Tweaks the area fill and image rendering algorithms to be a little more
    liberal with paint when being used to render characters.

    Changes the name of the 8-bit mapped color memory device from
    mem_mapped_color_device to mem_mapped8_color_device.

    Changes the memory devices so that on little-endian platforms, they can
    store the bytes within a word in either order.  (Little-endian order
    allows efficient 32-bit updating, big-endian is required when displaying
    or writing to a printer or a file.)

    Implements halftone phase.

    Replaces the trapezoid fill algorithm with a much more accurate one
    inspired by a contribution from Paul Haeberli.  This also changes the
    graphics convention back to filling only pixels whose center falls within
    the region to be filled.

    Changes the character cache to allocate headers and bits contiguously out
    of a single ring buffer.

    Changes gs_imagemask and gs_imagemask_init to take a thickness adjustment
    parameter.

    Changes gs_setcachedevice and gs_setcharwidth to take the graphics state
    as a parameter.

    Renames gx_device_memory_bitmap_size as gdev_mem_bitmap_size,
    mem_copy_scan_lines as gdev_mem_copy_scan_lines, and
    mem_bytes_per_scan_line as gdev_mem_bytes_per_scan_line.

## Version 2.1.1 (1/15/91)

This is a sub-release distributed to fix a few early bugs in 2.1, just in time for the new GNU master tape.

### Build procedures

    Removes all of the (undebugged) Level 2 code from the fileset, as well as
    the (unused) file gdevvga.c.

    Changes the tar file so that the files are stored in the directory
    gs<version> rather than simply gs, e.g., gs211.

### Interpreter

    Changes the scanner so that \ is recognized within strings regardless of
    whether the scanner is reading from a string or from a file.  This is
    compatible with newer P*stScr*pt interpreters, and with the newer
    P*stSc*pt language specification, but not with the older specification in
    the original PostScript Language Reference Manual.

### Drivers

    Fixes the max_value macro in gdevmem.c so that compilers won't complain
    about a left shift by 32.

    Adds 'byte' to the list of types that gdevx.c must sidestep because header
    files use them.

### Library

    Changes the computation of penum->unpack in gsimage.c so as not to upset
    compilers that don't treat procedures and pointers to procedures as
    compatible types for conditional expressions.

## Version 2.1 (12/31/90)

This is primarily a bug fix release to clean up problems in 2.0. It also implements a first cut at the new color operators.

### Build procedures

    Changes the separator for multiple directories in MS-DOS from ';' to '|',
    since there is no way to include a ';' in a command line.

    Adds <dir>/fonts to the default search path, where <dir> is c:/ghost for
    MS-DOS systems and `pwd` for Unix systems.

    Adds new documentation describing how to direct output to the printer.

    Changes the PROCTYPE and USE8087 options in MSDOS.MAK to CPU_TYPE and
    FPU_TYPE.  The latter now indicates the type of FPU to generate code for,
    if any.

### Drivers

    Adds a driver for the Canon BubbleJet BJ10e.

    Modifies the EGA driver to handle (non-standard) frame buffers larger than
    64K.  Adds drivers for the VGA and for the EIZO MDB-10 (a 1024 x 768 frame
    buffer).

    Changes the X driver so that it clips to the window dimensions, rather
    than reporting an error.

    Notes that the H-P LaserJet driver, like the DeskJet driver, works under
    Unix as well as MS-DOS.

    Adds support for 120 X DPI mode, and for the LQ-1500, to the Epson driver.

### Fonts

    Fixes bugs in bdftops:
    	- It was using /UniqueId instead of /UniqueID as the key for the
    font unique ID.  This effectively disabled the font cache.
    	- The definition for .notdef was bogus -- an invalid CharString.

    Changes ghost.ps and gfonts.ps so that NullFont is the initial font,
    rather than Ugly.

    Arranges things so that when attempting a font substitution, if the
    default font is not found, NullFont is used instead.

    Extends bdftops so that if certain easily synthesized characters are
    missing from a font, it will attempt to synthesize them using available
    characters.

### Interpreter

    Extends the -T switch to allow specifying a printf template for the
    arguments of the procedure being traced.

    Fixes bugs:
    	- /0 was interpreted as equivalent to 0 (a number) rather than a
    literal name.
    	- packedarray was defined as being like array, instead of like
    array followed by astore.
    	- Many minor and harmless type mismatches (and a couple of very
    minor genuine bugs) were upsetting the Apollo C compiler.
    	- exp was incorrectly failing in certain cases with a negative
    first argument.
    	- copyscanlines incorrectly required at least 4 elements on the
    operand stack, although it correctly only used the top 3.
    	- readhexstring incorrectly read 1 byte even if the string length
    was zero.
    	- Not every place that expected an array would accept a packed
    array.
    	- Very complex paths (and infrequently other things) could produce
    a 'memory leak'.
    	- / alone would skip following whitespace and gather following
    characters, rather than creating an empty name.
    	- ghost.ps left newerror defined as true in $error, which resulted
    in an erroneous error report if a program executed a 'stop'.
    	- The definition of exitserver in serverdict didn't clear the
    stack.
    	- currentfile returned an executable file, rather than a literal
    one.
    	- setfont for Type 1 fonts didn't check the UniqueID in the font
    dictionary against the one in the font's Private dictionary.
    	- A value stored in a dictionary under the key /xxx couldn't be
    retrieved using the key (xxx), and vice versa.
    	- charpath with a Type 1 font on a string containing a 'space'
    would produce garbage (it released the parent path inappropriately).
    	- bytesavailable did not work properly for terminal input.

    Changes the interface to the memory allocator so that it always takes an
    element size and an element count, like calloc instead of malloc (but note
    that alloc does *not* clear just-allocated blocks).  Gets rid of the
    special 'dynamic' allocation procedures.

    Changes the random number operators to use a better implementation.

    Changes the idiv operator so it will accept any numbers, not just
    integers, as arguments.  (The PostScript manual doesn't allow this, but
    implementations apparently do.)

    Provides semi-fake but usable definitions for all of the color PostScript
    extensions, including a real implementation of colorimage.

    No longer uses the name 'null', which is apparently reserved by Microsoft
    C.  Makes a number of other minor changes required to pacify the Microsoft
    C compiler.

    Implements %statementedit and %lineedit.  (%statementedit is equivalent to
    %lineedit, which is wrong.)  Changes the interactive interpreter to use
    %statementedit.

    Changes the scanner to accept null, ctrl-K (vertical tab), and ctrl-L
    (form feed) as whitespace.  Ctrl-L terminates a comment, null and ctrl-K
    do not.

    Allows a literal string as the 'proc' argument(s) for image, imagemask,
    and colorimage.

    Adds the following operators/procedures: arct, cleardictstack, deletefile,
    renamefile.

    Defines =print as a synonym for =, for the benefit of LaserPrep.

    Implements non-zero PaintType for the show operators (but not for
    charpath) for Type 1 fonts.

    Adds the ISOLatin1Encoding encoding vector.

    Renames currentcolor and setcolor as currentgscolor and setgscolor, to
    avoid conflict with the Level 2 PostScript names.  Removes colorhsb,
    colorrgb, hsbcolor, and rgbcolor.

### Library

    Fixes bugs:
    	- In a couple of places, a 0 was being passed as a pointer
    argument without casting, which confused the Microsoft C compiler.
    	- Image devices were not recognized properly in debugging
    configurations.
    	- Inverted-color monochrome image devices were not recognized
    properly.
    	- Images that exactly fill the drawing area rendered very slowly,
    because they erroneously used the general clipping algorithm.
    	- Images that are 1-for-1 with the device were incorrectly scaled
    by a factor of 8 in X.
    	- Rounding artifacts sometimes caused characters to be unevenly
    offset vertically by 1 pixel.
    	- Type 1 fonts that used the Flex feature resulted in garbled
    images.
    	- The show operator routines would incorrectly fill or stroke a
    path that existed at the time the show was started.
    	- setscreen truncated the cell size instead of rounding, which
    could produce off-by-1 anomalies.
    	- stroke would sometimes produce garbage (or nothing at all) for
    very narrow lines.
    	- path filling would only color the pixels whose centers fell
    inside the path: the Adobe specification requires coloring a pixel if any
    part of it falls inside the path.

    Changes the Epson printer driver so that it drives the printer directly
    rather than writing to a file.

    Changes pathbbox so that if the path is empty but there is a current
    point, it returns a null rectangle at the current point.

    Changes gs_image_init to take an additional parameter (after bps) giving
    the number of samples per pixel (1, 3, or 4), and an indication of whether
    the samples for each pixel are together or separated (-3 or -4).

    Renames the gs_image_data and gs_imagemask_data procedures as gs_image and
    gs_imagemask, and removes the old versions of the latter.

    Adds gs_colorimage.

    Replaces Snoopy's color dithering algorithm with one contributed by Paul
    Haeberli.

    Changes gs_setgray, gs_[set]hsbcolor, and gs_[set]rgbcolor so that they
    coerce arguments outside the range [0..1] back into the range, instead of
    signalling an error.

    Makes a number of minor changes required to pacify the Microsoft C
    compiler.

    Changes gs_arcto so that if the last argument is a null pointer, the
    tangent points are not returned.

    Removes gs_type1addpath, which is not useful.  (Clients must call
    gs_type1_init and gs_type1_interpret directly.)

    Implements the 'seac' opcode for Type 1 fonts, allowing fonts with accented
    characters to display properly.

    Implements the undocumented 'testadd' opcode for Type 1 fonts, which is
    used by some Adobe fonts.

    Renames gs_currentcolor and gs_setcolor as gs_currentgscolor and
    gs_setgscolor.  Removes gs_colorhsb, gs_colorrgb, gs_hsbcolor, and
    gs_rgbcolor.

## Version 2.0 (9/12/90)

The main purpose of this release is to add fonts, support for multiple devices, and imaging into memory. It also fixes a number of miscellaneous bugs. (Unfortunately, accurate records of the bugs fixed are not available.) The changes were so extensive that we chose to increment the major version number.

### Miscellaneous

    Doesn't attempt to open the .MAP file on Unix systems.

    Adds mention of statusd.ps to interp.doc.

    Notes that Turbo C 2.0, not 1.5, is required for building the MS-DOS
    version.

    Adds a DEVICES= line to the makefile, and allows multiple devices.

    Documents, in interp.doc, the X Windows resources that Ghostscript
    recognizes.

    Adds three PostScript masters to the fileset: chess.ps (+ cheq.ps),
    golfer.ps, and escher.ps.

### Drivers

    Changes the names of all the device drivers.  See gdevs.mak for the
    updated list.

    Adds a (working) driver for SunView.

    Adds drivers for the Sony NeWS frame buffer, and the Sony Microsystems
    NWP533 printers.  These drivers were contributed by users, so we aren't
    prepared to answer questions about them.

    Adds a driver for the Borland Graphics Interface (BGI) for MS-DOS systems.
    Note that to use this driver with a non-EGA/VGA display, you need a .BGI
    file appropriate for your hardware.  (The Ghostscript executable includes
    the EGA/VGA driver.)

    Adds a driver for Epson printers.  The driver has only been tested on an
    LX-800, and on an H-P DeskJet in FX-80 emulation mode, but may work on
    other models.  The driver could be adapted to work on Unix systems, but as
    distributed, it only works on MS-DOS systems.

    Adds a driver for the Hewlett-Packard DeskJet printer.  The driver could
    be adapted to work on Unix systems, but as distributed, it only works on
    MS-DOS systems.

    The X Windows driver no longer waits for the user to type a character
    before bringing up the initial display.

    Adds information to drivers.doc describing how to change the definition of
    the device structure and procedure table.

    Extends the tile_rectangle and tile_trapezoid driver procedures to
    interpret color0 = color1 = gx_no_color_index as meaning that the tile is
    actually colored, not a mask.

### Build procedures

    Changes the tar file so it puts everything in a directory called gs.

    Removes the -ansi switch for gcc (this was causing problems with <math.h>
    on some systems).

    Changes LDPLAT to the string -X, which is appropriate for most Unix
    systems (but not for SunOS 4.n).

    Adds EXTRALIBS to the makefile, for specifying additional libraries to be
    linked in.

    Adds a 'clean' target for 'make', to get rid of all temporary files, the
    binaries, and the executable.

    Changes names of system-specific files from gp-xxx.c to gp_xxx.c.

    Adds support for VMS (gp_vms.c and ghost.dcl).

    Creates a new file gdevs.mak, and reorganizes the other makefiles, so that
    the choice of which device driver(s) to include is isolated in a single
    line in the platform-specific makefile.

    Changes the standard MS-DOS makefile so it builds for 8088/86 (not 80386),
    with neither -DNOPRIVATE nor -DDEBUG.

    Changes the name of the MS-DOS makefile from dos-ega.mak to msdos.mak, and
    the Unix makefiles from ux-[g]cc-x.mak to unix-[g]cc.mak.

    Updates drivers.doc to describe how to add new drivers in gdevs.mak.

    Removes gdevs.ps: the drivers are now responsible for specifying the size
    of the imaging region.

### Interpreter

    Adds a makefile macro GS_LIB_DEFAULT and an environment variable GS_LIB to
    define a search path for the library (initialization and font) files, and
    implements the -I switch for the same purpose (replacing -sLIB=, which was
    never actually implemented).  See interp.doc for details.

    No longer clears the operand stack between interactive inputs.  No longer
    prints the contents of the operand stack after every input in debug mode.

    Doesn't "eat" the character that the user types to proceed after a
    showpage, unless it's an isolated <return>.

    Changes the prompt so that it says
    	GS>
    if the operand stack is empty, or
    	GS<n>
    if there are n > 0 elements on the operand stack.

    Adds -w and -h switches to the command line, equivalent to -dWIDTH= and
    -dHEIGHT= except that they require numeric arguments.

    Adds -q (quiet startup) switch to the command line, which suppresses some
    initial messages and also has an effect equivalent to -dQUIET.

    Fixes bugs:
    	- = and == caused an error on some kinds of objects if the object
    didn't have read access.
    	- cvs didn't print operator names.
    	- The definition of dynamic_begin in iscan.c caused the DEC VMS C
    compiler to produce incorrect code.
    	- mul didn't return a correct (real) result when multiplying a
    very large integer by an integer that wasn't very large.
    	- eq and ne didn't work on files, fonts, save objects, and some
    operators.
    	- The scanner would sometimes blow up on floating point numbers
    beginning with a '.'.
    	- flushfile didn't pop its argument from the stack.
    	- put and putinterval would store into a packed array.
    	- a few operators didn't check properly for stack underflow.
    	- cvrs produced wrong output for radix values greater than 10.
    	- The scanner would convert upper-case letters in alternate-radix
    numbers wrong on Unix systems.
    	- String comparisons other than equality often produced the wrong
    result if the strings were of different lengths.
    	- An ifelse as the last thing inside a forall would confuse the
    execution stack.
    	- There were some omitted casts and 'private' declarations that
    made the GNU compiler unhappy.
    	- There was a memory leak in the image[mask] operators that caused
    516 bytes to be permanently lost each time one of them was used.
    	- Quoted strings of length greater than 50 and less than 100 would
    get mangled when being read in.
    	- The scanner didn't consume the whitespace character following a
    token, so programs that read data out of the program file could get
    confused.
    	- Under rare circumstances, an object of size between 249 and 255
    bytes could get allocated on top of another object.

    Allows bind to bind packed arrays, even though they aren't normally
    writable.

    Changes the length operator to allow a name as the argument.  (The
    PostScript manual doesn't allow this, but implementations apparently do.)

    Changes the setcachedevice operator to allow the bounding box to be
    specified as a 4-element array instead of 4 scalars.  (The PostScript
    manual doesn't allow this, but implementations apparently do.)

    Removes a line from ghost.ps that accidentally disabled the font cache.

    Implements memory devices (makeimagedevice, copyscanlines, and makedevice
    for image devices).  makeimagedevice is implemented only for 1, 8, 24, and
    32 bits per pixel.

    Changes the deviceparams operator so it pushes a mark on the stack below
    the parameters.  This is to allow for devices that have more than the
    standard set of parameters.

    Replaces defaultdevicename with two new operators, getdevice and
    devicename.

    Adds a flushpage operator that flushes any outstanding buffered output to
    the screen.  This is not the same as copypage: on printers, copypage
    actually prints a page, whereas flushpage may do nothing; on displays,
    flushpage and copypage may both flush output to a server.

    Adds an unread operator for pushing back a character into a file.

    Adds a description of proposed grayimage and colorimage operators to
    ghost.doc, even though they aren't implemented yet.

    Changes the name of the currentfileposition operator to fileposition.

    Removes the framedevice operator, since the new device operators supersede
    it.

    Adds a writeppmfile operator, for writing the contents of a memory device
    to a ppm file.

    Makes Ghostscript work even when the >> operator doesn't sign-extend
    negative numbers.  (This has not been tested.)

    Adds the Symbol encoding to ghost.ps.

    Adds two new file-related operators, filename and findlibfile.  See
    ghost.doc and interp.doc for details.

    Adds type1encrypt and type1decrypt operators for manipulating Adobe Type 1
    encoded fonts.

    Changes the imagecharpath and addcharpath operators to type1imagepath and
    type1addpath.  These operators now work with the Adobe Type 1 font
    encoding.

    Adds the type1decryptfile operator for reading Adobe Type 1 encrypted
    fonts.

### Library

    Fixes bugs:
    	- curveto and lineto didn't check for the current point being
    defined.
    	- stringwidth would fail if there was no current point.
    	- There were omitted casts that made the GNU compiler unhappy.
    	- Line caps and joins didn't always work.
    	- Dashed lines didn't work at all.
    	- If you read out the current matrix while inside a BuildChar
    procedure, the result was garbage.
    	- image[mask] would crash if you gave it a single string with more
    than 64K-1 pixels (MS-DOS only).
    	- Filling with a gray pattern sometimes wrote into pixels beyond
    the right edge of the region (MS-DOS only).
    	- The font cache would mistake fonts for each other if both fonts
    had a default (unsupplied) "unique ID".
    	- When a character was entered into the font cache for the first
    time, sometimes it would display as garbage and/or displaced vertically
    from its proper position.

    Implements gs_makeimagedevice, gs_copyscanlines, gs_getdevice,
    gs_devicename, gs_flushpage, gs_writeppmfile, gs_type1encrypt,
    gs_type1decrypt, gs_type1imagepath, and gs_type1addpath procedures
    corresponding to the new operators in the interpreter (see preceding
    section).

    Changes [gs_]setdevice so that it does an erasepage when it first opens
    the device.

    Changes definition of gx_device structure as follows.  NOTE: THIS AFFECTS
    ALL DRIVERS.

    	- Removes bits_from_MSB (which wasn't actually used, in any case).
    	    Ghostscript now assumes officially, as it always did in
    	    practice, that device bitmaps are stored MSB first, i.e., X=0
    	    corresponds to the 0x80 bit in the first byte.

    	- Removes the initial_matrix member, which wasn't actually being
    	    set up.

    	- Adds a new member 'name', a string giving the device name.

    	- Adds new members 'x_pixels_per_inch' and 'y_pixels_per_inch'.
    	    These are only used by the default initial_matrix procedure
    	    (see below).

    	- Adds a new procedure 'output_page'.  The default implementation
    	    (gx_default_output_page) just calls the sync_output procedure.

    	- Adds a new procedure 'get_initial_matrix'.  The default
    	    procedure uses the width, height, and x/y_pixels_per_inch
    	    members to compute the matrix, assuming that X values run from
    	    right to left, and Y values run from top to bottom.

    Changes the names of the allocation procedure types gs_proc_alloc and
    gs_proc_free to proc_alloc_t and proc_free_t, and moves them from gs.h to
    std.h.

    Makes Ghostscript work even when the >> operator doesn't sign-extend
    negative numbers.  (This has not been tested.)

Copyright © 2000-2006 Artifex Software, Inc. All rights reserved.

This software is provided AS-IS with no warranty, either express or implied. This software is distributed under license and may not be copied, modified or distributed except as expressly authorized under the terms of that license. Refer to licensing information at http://www.artifex.com/ or contact Artifex Software, Inc., 7 Mt. Lassen Drive - Suite A-134, San Rafael, CA 94903, U.S.A., +1(415)492-9861, for further information.

Ghostscript version 9.15, 22 September 2014