CP/M/CPM_CDROM.iso/enterprs/cpm/utils/s/unarc14.arc/UNARC.HIS

Text File | 1993-03-28 | 8.3 KB | 175 lines

File:     UNARC.HIS
Subject:  Modification History of UNARC Program
Version:  1.4
Date:     November 21, 1986

The following provides a detailed history, in reverse chronological
order, of the modifications made in each release of the UNARC program
(as extracted from the source program file for the current version 1.4
release).

------------------------------------------------------------------------

1.4    21 Nov 86  (RAF)

We had hoped NOT to release another update of this program, but to
replace it entirely by three new programs with enhanced functionality
(UNARK, ADIR, and ATYPE), in conjunction with the upcoming release of
the CP/M archive file builder (NOAH).  However, (sigh).....

Corrects bug (exhibited with .ARC's created by version 1.1 or later of
Phil Katz' PKARC program for MS-DOS) which caused files to be extracted
incorrectly (with output file length and CRC warnings) due to string
table reset codes appearing early in crunched files (i.e. before the
output code length reaches 12 bits).  Thanks to Keith Petersen for
identifying and notifying us of this problem.

And, while we're at it.....

Adds paging of all displayed output, controlled by non-zero patch byte
specifying screen lines between pauses (TYLPS, default value = 23).
This is essentially the feature added by 'Larry Smith' (see version 1.3
below), but we've been able to do it (with enhancements) and still keep
the (Z80 version) .COM file below 4K (just!).  Causes '[more]' message
to appear at bottom of screen.  Space bar scrolls one more line, ^C
aborts, anything else scrolls one more screenful.  (LINE FEED may be
used to avoid overprinting the '[more]' line.)  May be defeated for
continuous typeout by trailing 'N' (after a blank) on command line.

Also:

- If archive filetype omitted, and the default .ARC filetype not found,
  tries .ARK as an alternate default.  (Anticipates NOAH, and compatible
  with Irv Hoff's KMD22.)

- Incorporates option to bypass BDOS function 31 call (Get DPB Address),
  for non-std CP/M clones such as Cromemco CDOS and CP/M-68K emulator
  for 8080 CP/M 2.2.  (Eliminates UNARC12 patch notice, UNARC-P1.NOT.)

- Allows program name to be patched (at start of USAGE message).
  Affects all help screen references and abort message.  (E.g., RCP/M
  sysops may prefer 'ADIR' to 'UNARC'.)

- Corrects count of bytes skipped due to invalid header when processing
  'self-unpacking' archives with more than 3 preliminary bytes.

- Enhances recovery processing for invalid archive headers, and merges
  'invalid format' and 'unexpected eof' errors.  This change tends to
  cause display of a garbage directory entry (before abort) for non-ARC
  files, but it does allow processing of certain new self-unpacking
  archives, such as Phil Katz' PKX32A11.COM.

- Changes the replacement for an invalid filename char from '_' to '$'
  (since underline is not allowed as a filename char by CP/M CCP, and
  '$' usually carries a 'temporary' significance in CP/M).

- Reduces directory listing width by one column (78 now), to allow
  one more char without extra blank line on terminals which autowrap
  after column 80 (e.g. allows leading semicolon generated by MDM7 and
  IMP during disk file capture of terminal output).

- Adds a few bells to warning and fatal messages, along with a patch
  byte to disable these (for those who prefer solitude).

- Allows ^K in addition to ^C for program abort requests.  (For certain
  ancient RCP/M systems which never pass ^C back to user programs.)

- Adds .ARK and .?Z? (CP/M CRUNCH or MS-DOS ZOO 'Z format' files) to
  list of excluded typeout extensions, and eliminates .CMD (since that
  might be a readable dBASE command file instead of CP/M-86 binary).

- Simplifies the Z80 CPU check and removes the 'Z80 Version' message
  in the help display, to save a few bytes in that version.  (Alternate
  version, UNARCA.COM, now displays '8080 Version'.)

- Adds 8080 version message recommending Z80 version, when run on a Z80.


1.3    --none--   (RAF)

This version bypassed due to appearance of several unauthorized updates
with the name UNARC13 (and not because of superstition).  Most notably,
these include Steve Sanders' unnecessary addition of ^S and ^C checking
during file typeout (because TurboDOS does not properly emulate CP/M's
handling of these in BDOS function 2 calls), and the addition of paged
typeout by 'Larry Smith' (whoever he is; a worthwhile enhancement, but
the release was deficient in several other respects).  WHY CAN'T THESE
'CONTRIBUTORS' SIMPLY CONTACT THE AUTHOR BEFORE RELEASING THEIR CHANGES
TO THE PUBLIC?!


1.2    24 Jun 86  (RAF)

Modified to allow assembly of a version which will execute on 8080/8085
CPU's.  (We resisted this initially but have been made to realize that
this is necessary to achieve true acceptance of UNARC by the full CP/M
user community.  Non-Z80 users, particularly RCP/M sysops, still exert
considerable influence in the world of public domain software.  This,
we believe, is out of proportion to their numbers, since almost all
CP/M systems sold in the last five years are Z80-based.  Nevertheless,
we've accommodated the needs of these users by extensive use of macros
which serve to emulate Z80 instructions on non-Z80 machines.)  However,
no attempt has been made to optimize for either size or speed in the
non-Z80 version (which is 1K larger and 50% or more slower than its
Z80-only counterpart).

Also:

- Implements a "wheel" byte to simplify use and installation on RCP/M's.
- Lines up file types in directory listing.
- Permits processing of "self-unpacking" archives such as the MS-DOS
  ARC512.COM file (anticipates a future scheme for distributing UNARC).
- Attempts to recover from bad archive headers by skipping extra bytes.
- Eliminates archaic "T:" syntax completely for file typeout.


1.1    24 May 86  (RAF)

Minor change to allow file typeout without the "T:" syntax (which
didn't work with almost ANY CCP replacement)...  File will be typed if
it:  (1) has no disk drive name, (2) is a single (UNambiguous) file,
and (3) is not an excluded filetype.  (Else, file will simply be listed
with no error message.)  This change was suggested by Irv Hoff's mod to
UNARC10, which he called ADIR.  (Previous "T:" method can still be
enabled, but it is now undocumented since we will probably drop it
altogether in future.)

Also shortened on-line help message, so that COM file size is now
reduced to 4K.  (For RCP/M systems, if HODRV = 0 and/or TYFLG = 0, the
help information relating to disk extraction and/or file typeout,
respectively, is automatically removed.)


1.0    03 May 86  (RAF)

First public release.  Supports file formats generated by all versions
of MS-DOS ARC through (at least) version 5.12 dated February 7, 1986.


0.0    01 Mar 86  (RAF)

I undertook writing this program to satisfy my curiosity about software
developments in the MS-DOS/PC-DOS world.  The ARC "freeware" program
(copyright by System Enhancement Associates) has been around for over a
year now and has achieved enormous popularity in the 16-bit community.
Unfortunately, the lack of a compatible equivalent for CP/M systems
renders a large amount of public domain software inaccessible to 8-bit
users such as myself.  (Note that 16-bit software can indeed be usable
on 8-bit systems, e.g. Pascal and C language programs.)  Also, an
increasing number of RCP/M systems are catering to both 8-bit and
16-bit users, and it is my hope that UNARC may find a welcome home on
such systems.

Note that I was not (initially) a fan of the sequential .ARC file
format, which is less flexible and slower to process (though certainly
more compact) than the random-access format which Novosielski .LBR
libraries have provided for years.  Therefore, I stopped short of
producing a complete ARC program equivalent which includes creation of
.ARC files.  The LZW "crunching" algorithm is impressive though (see my
editorial comments preceeding the UCR routine), and I now believe there
is a place for .ARC files in the CP/M world (particularly on RCP/M's,
where the name of the game is reducing upload/download time).  But
that's the domain of another program (i.e. my next project: NARC).

                    - Bob Freed