The following changes have been made in version 2.04e of
PKZIP/PKUNZIP from version 2.04c.
1) DPMI.
The DPMI support in PKZIP/PKUNZIP has been changed to work
around bugs and anomolies with the following DPMI drivers or
environments. PKWARE would like to thank Quarterdeck Office
Systems and Qualitas, Inc. for their technical assistance
regarding DPMI.
a) PC-KWIK
According to PC-KWIK corporation's document, 'PC-KWIK
Technical Issues "Summer '92"':
PC-KWIK is unable to recognize memory requests from programs
using VCPI or DPMI protocols ... For programs [that use VCPI
or DPMI] it is necessary to reduce the size of the cache and
disable lending.
PC-KWIK has a lending feature that allows memory to loaned
from the cache memory to applications. However, PC-KWIK is
not aware of any memory allocated or used by DPMI, and will
loan this memory as well, possibly causing corruption of the
DPMI driver and usually resulting in a system crash or reboot.
This problem seems to present in most versions of SUPERPCK,
through version 5.01.
In other words, when using PC-KWIK with any program that uses DPMI,
including PKZIP and PKUNZIP, you should either make sure that you
have enough memory in your computer so that lending will not occur,
reduce the size of your cache, or disable PC-KWIK's lending.
Therefore, PKZIP/PKUNZIP detect for the presence of PC-KWIK
and default DPMI to DISABLE when PC-KWIK is installed. This
can be overidden by specifying -)+ on the PKZIP or PKUNZIP
command line, or by placing DPMI=ENABLE in your PKZIP.CFG for
PKZIP or setting the environment variable PKUNZIP=-)+ for PKUNZIP.
b) QDPMI 1.00
If a program tries to use DPMI and EMS memory with QDPMI 1.00,
QDPMI would become unstable or crash. PKZIP/PKUNZIP now
check for the presence of QDPMI 1.00 and if PKZIP/PKUNZIP
are using EMS memory, they do not attempt to use DPMI at all.
c) QDPMI 1.01
When a program switches to protected mode, QDPMI does not
'synchronize' the EMS page frame. The result is that programs
can not correctly read or write any data in the EMS page frame
while in proteced mode. PKZIP/PKUNZIP now check for the presence
of QDPMI 1.01 and will use slower real-mode code for any
manipulation of data in the EMS page frame rather than faster
protected mode code.
d) OS/2 2.0 DOS BOX
The OS/2 2.0 DOS box does not allow programs to allocate the
'DPMI private data area' in an UMB. Doing so causes a system
violation error. PKZIP/PKUNZIP now check to see if they are
running in the OS/2 2.0 DOS box and will not allocate the DPMI
private data area in an UMB. (This is actually kind of a shame,
as the OS/2 DOS box (unlike the Windows DOS box) provides UMB
memory to DOS applications. It should be able to allow programs
to store the DPMI data area in these UMB's.)
e) Windows 3.0 DOS BOX
The DPMI support in the Windows 3.0 DOS box does not always
seem to work correctly. Therefore, PKZIP/PKUNZIP detect if
they are running in the Windows 3.0 DOS box and will not support
DPMI in this environment.
f) Windows 3.1 DOS BOX
The way PKZIP/PKUNZIP allocates the DPMI save/restore state
buffer has been changed to be more compatible with Windows 3.1.
2) The Norton AntiVirus program FALSELY reported that PKZIPFIX and
PKUNZIP contained the Maltese Ameoba virus. The software DID
NOT contain this virus. All files in this release have been
modified so as to not trigger any FALSE virus reports by the
Norton AntiVirus program.
3) QEMM versions 5.1x would corrupt the high word of the 32-bit
registers on an 80386 or 80486 CPU. PKZIP/PKUNZIP check for
this condition, and will not use 32-bit instructions if QEMM
version 5.1x is present.
4) Apparently some peer-to-peer networks such as Novell Netware Lite
and others do not support canonical or fully specified filename.
PKZIP now uses noncanonical filenames when specifying temporary
filenames on a network drive to avoid this problem.
5) PKZIP would erroneously report "E28 Destination is same as temp
directory" when creating a new .zip file on drive A:. This has
been fixed.
6) The keywords on/enable and off/disable are now synonymous when
used in the PKZIP configuration file.
7) Using EMS= options in the PKZIP configuration file would enable
or disable both EMS and XMS usage. The XMS= option had no effect.
This has been corrected.
8) The Quick format option in PKZIP would zero out the existing FAT
on the disk (by design). However, if the disk had any bad
sectors on it (in which case, it isn't a good idea to use that
disk as a backup disk anyway...) they would now be marked as
good. By popular demand, PKZIP now reads the existing FAT and
leaves any bad sectors marked as bad. This however, makes the
'Quick' format function about twice as slow as it was (although
still much faster than an unconditional format). In most cases
however, unless there are several subdirectories on the diskette,
the -&w (wipe) option is faster than the -&f (format) option when
backing up to pre-formatted diskettes.
9) Under some cirumstances, PKZIP could possibly store the last
file in a multi-disk backup set incorrectly. This has been
corrected.
10) The volume label option in PKZIP would not work. This has been
fixed.
11) PKZIP/PKUNZIP now searches for a PKNOFASTCHAR variable in the
DOS environment. If this variable is present, PKZIP/PKUNZIP
will use the slower DOS 1.x/2.x character output functions
rather than the 'DOS Fast Character Output' function. This is
provided for compatability with some TSR's, BBS Doors and mail
readers etc., that redirect or capture the output of programs and
do not support the DOS Fast Character Output function.
12) PKZIP will now accept either MAXIMUM or MAXIMAL in the
configuration file.
13) Some people have requested that the -& backup option support the
DOS verify function. Specifying -&v on the PKZIP command line
or BACKUP=VERIFY in the PKZIP.CFG file will turn on the DOS
verify flag when writing to the backup disk(s). This makes
PKZIP run slower, but ensures better integrity of each diskette.
14) Using the -m option with -rp in PKZIP will delete any empty
subdirectories that have been saved in the .ZIP file after all
the files have been moved into the .ZIP file. Some people have
requested a way to have PKZIP leave these empty subdirectories
behind. This can be accomplished by using -m- on the PKZIP
command line.
15) It appears that some versions of NoGate's PAK program would
place incorrect information in the .ZIP file directories that it
created. Specifically, the disk number information for where
files, the central directory, and the central end directory
started is inconsistent, causing PKUNZIP to think it was
extracting a multi-disk .ZIP file when it really wasn't.
PKUNZIP now checks for this condition, and ignores this
erroneous information.
16) PKZIP now ignores any ZIPDATE= or -o or -k options when creating
multi-disk .ZIP files, rather than displaying the help screens.
17) On some 80386 machines running PKZIP could leave allocated UMB's
behind. This has been corrected.
18) In some circumstances, running PKZIP with EMS memory and very low
free conventional memory could cause corruption of the .ZIP file.
This has been corrected.
19) When PKZIP prompts for an encryption password, it will now ask the
user to enter the password twice for verification.
20) PKZIP/PKUNZIP would not work under DOS 2.x. This is because
DOS 2.x crashes on many int 2Fh installation check calls for
EMS/XMS drivers etc. These calls work properly under DOS 3.0
or above. Therefore, PKZIP/PKUNZIP detect for the presence
of DOS 2.x, and will not support any of the advanced features
including 32-bit instructions, EMS memory, XMS memory, DPMI
support and Netware usage.
21) PKSFX could in some instances erroneously report failed AV's or
garble any AVEXTRA text present. This has been fixed.
22) Using PKZIP with the -o option or ZIPDATE=LATEST in the configuration
file would set the date of the .ZIP file to the latest dated file
or directory. Directory dates are now ignored in this version.
