Dec 142017
JAM 1.19, shareware (cheap) stacker like transparent disk compression, driver is only 32K of memory, fast defrag, 2:1 compression (and better), worth the download.
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JAM 1.19, shareware (cheap) stacker like transparent disk compression, driver is only 32K of memory, fast defrag, 2:1 compression (and better), worth the download.
File Name File Size Zip Size Zip Type
AUTHORS.DOC 1710 909 deflated
EXTEND.BAT 1563 583 deflated
JAM.DOC 185157 46675 deflated
JAM.SYS 12621 8746 deflated
JCHKDSK.COM 31080 19154 deflated
JCMD.COM 1769 1338 deflated
JCREATE.COM 15455 9500 deflated
JDIR.COM 16778 11012 deflated
JMAX.COM 17408 11116 deflated
JMOUNT.COM 13977 9127 deflated
JSIZE.COM 15938 10155 deflated
JSWAP.COM 2501 1881 deflated
README.DOC 32829 10880 deflated
REGISTER.DOC 4504 1768 deflated
TPCREAD.ME 199 165 deflated

Download File JAM119SW.ZIP Here

Contents of the README.DOC file


JAM (tm) Version 1.19 Release Notes (Jul 21 1994)

This file contains the following topics:

1. Release highlights
2. Files on the distribution disk
3. Upgrading the JAM from an older version
4. Getting started
5. Compatibility with certain software utilities
5.1. DOS versions
5.2. Memory managers
5.3. Viruses & Anti-virus Software
5.4. Stacker and other disk compressors
5.5. Networks
5.6. Disk repairing/defragmentation utilities
5.7. Disk Cache utilities
5.8. Data encryption software
5.9. Windows 3.xx
6. Possible problems
6.1. JMOUNT displays the message "Archive file is too fragmented".
6.2. Your program tells that the JAM drive is write-protected.
6.3. You find that your JAM drive mounting as a read-only disk.
7. Addendum to the JAM User's Guide
7.1. The JSIZE utility
7.2. The JSWAP utility
7.3. The JCMD utility
8. Technical support

1. Release Highlights

This new (1.19) release features several advantages over previous

* Extendable archive files support (now, you can easily change the
size of JAM archive files!)

* Removable drives support (JAM can work with archive files located
on diskettes, Bernoulli drives, PCMCIA cards, etc.)

* Improved JCHKDSK utility (compatible with DR/Novell-DOS DELWATCH
feature, advanced recovering strategy, etc.)

* Extended syntax and functions of the JCREATE utility

* New JCMD utility -- automatically replaces DOS "DIR" and "CHKDSK"
commands by JAM JDIR and JCHKDSK utilities.

* Easy to read output of the JCHKDSK, JCREATE, JDIR, and JSIZE
utilities (added thousands separators when displaying numbers)

The following advantages, are also available since release 1.10:

* Large hard drives support (you can use up to ten 512Mb JAM drives
simultaneously, i.e. up to 5Gbytes of hard disk space)

* Superior Speed due to improved implementation of a compression
algorithm built-in JAM device driver

* Superior Compression - new recompression method in JMAX utility
allows you to add up to 20% more disk space

* Reduced memory consumption (32Kb or just 24Kb (for drives with
4Kb clusters) when loaded in conventional memory!)

* "LOAD-HIGH" function support for loading the driver into high

* "DirectWrite" protection feature (prevents problems with some
ill-behaved programs, viruses, etc.)

* Extended syntax and functions of the JMOUNT utility

* New JSWAP utility allows you to interchange the drive letters
of any two drives (for instance, JAM drive and its Host drive)

* Full compatibility with Novell DOS 7 and MS-DOS 7.0

* DOS based Local Area Networks (LANs) support.

2. Files on the disk

The JAM 1.19 distribution contains the following files:

README.DOC This file
JAM.SYS The JAM device driver
JCREATE.COM JAM archive files creation utility
JMOUNT.COM JAM drives mount/dismount utility
JSIZE.COM Archive size modification utility
EXTEND.BAT An automatic JAM drive extension utility
(and an example on using JAM utilities in batch files)
JDIR.COM Extended directory display utility
JCHKDSK.COM Drive maintenance utility
JCMD.COM JAM interceptor (replaces DOS "DIR" and "CHKDSK" commands)
JMAX.COM JAM drives recompressor/defragmenter
JSWAP.COM Drive swapper
JAM.DOC JAM User's Guide
REGISTER.DOC JAM registration information
AUTHORS.DOC List of people involved in the development of JAM 1.19

3. Getting Started

The following steps should be taken before you start:

1. Check your file system integrity by CHKDSK (or ScanDisk) utility

2. Defragment your hard disk drives using a disk optimization utility
like Gazelle System's OPTune, Norton Utilities' SPEEDISK, Central
Point Software' COMPRESS, etc.

3. Copy the JAM files (see above) on your hard disk

4. If you use Windows 3.xx -- add the following command to
the SYSTEM.INI file (in the [386Enh] section):


See also the Section 5.9. below.

5. Check your system configuration (files CONFIG.SYS and AUTOEXEC.BAT)

5.1. If you have installed the JAM with version prior 1.05, please
read the Section 4. "Upgrading the JAM from an older version".

5.2. If you have installed QEMM 7.0x with enabled DOS-UP feature,
please read the Section 5.2. in this file.

5.3. If you have installed Stacker, DoubleSpace, SuperStor, or
other disk-compression system, read the Section 5.4. below.

5.4. If you use a disk cache utility, read the Section 5.7.

6. Install the JAM, using the instructions in JAM.DOC Chapter 2 -
"Getting Started With the JAM". Note, that now you can also create
extendable archive files (use JCREATE with /X switch). This allows
you make a small archive file, using available free space on your
hard disk, then move some files from the host drive on the JAM one,
then extend size of JAM archive (using JSIZE utility), and so on.
The same technique can be applied to deinstallation as well.

4. Upgrading the JAM from an older version

This version of the JAM is NOT COMPATIBLE with versions prior 1.05 !
If you are upgrading the JAM from an older version, you should BackUp
the files on the existing JAM Drives, delete corresponding Archive Files,
install new version of the JAM, and restore files you have BackUp.

5. Compatibility with certain software utilities

5.1. DOS versions

The JAM 1.19 is fully compatible with the following Disk Operating Systems
(Control Programs):

1. PC-DOS 3.30, 5.02, 6.01
2. MS-DOS 3.30, 4.01, 5.0, 6.0, 6.2, and 7.0beta (January 1994)
3. Compaq DOS 3.31, 5.0
4. DR-DOS 6.0 (April 1992 and earlier releases)
5. Novell DOS 7

NOTE: To prevent possible conflicts with other Disk Operating Systems,
we have not tested, JAM driver checks the DOS OEM number. If DOS version
is between 3.30 and 7.0, but OEM number is neither 00h (IBM), 01h (Compaq),
nor 0FFh (Microsoft), the JAM driver will display error message like:

'Warning: Incorrect DOS OEM number.'

In this case (or in case if you have newer release of PC-DOS, MS-DOS, or
Novell DOS than listed above) you could contact us for upgrade information
(see section 8. Technical Support below).

5.2. Memory managers

The JAM 1.19 is compatible with all memory managers we have tested
including HIMEM, EMM386 (supplied with PC-DOS, MS-DOS, DR-DOS, and
Novell DOS), QEMM386 and 386MAX. Occasionally, the memory manager will
require special parameters to work properly, or you will need to change
order of loading the JAM components.

Some detailed information about particular products is given below:

The JAM is fully compatible with Quarterdeck's QEMM 5.0-7.0+,
including such new technologies as Stealth ROM and DOS-Up features.

If you want to load portions of DOS into upper memory, using the
QEMM 7.0+ DOS-Up program, you should ensure that there is no lines


or (in case of DR-DOS or Novell DOS 7)


in your CONFIG.SYS file. The point is that DOS-Up is incompatible
with DR-DOS's INSTALL command, and with similar loading method used
by JMOUNT and JCREATE utilities. If you are using either of these
commands in your CONFIG.SYS file, load the JMOUNT and/or JCREATE
utilities from AUTOEXEC.BAT instead.

The JAM is fully compatible with Qualitas's 386MAX (6.0-7.0) memory
manager, running on PC with MS/PC-DOS 5.0 or Novell DOS 7 and higher
in use. If you run 386MAX with one of the older PC/MS/DR-DOS versions,
the JAM.SYS device driver cannot be loaded into upper memory.

5.3. Viruses & Anti-virus Software

Unlike other real-time compressors (e.g. Stacker or XtraDrive) the JAM does
not modify boot-sector parameters during initialization. So, you may use
any virus detector without any restriction (and possibility to see
annoying messages like 'Brand X has detected a program trying to write to
the boot record.' during each system start-up :-).

If your machine has a virus, the JAM can affect the way the virus writes
itself on disk and/or an anti-virus corrects this. For example, JAM's
[DirectWrite] protection feature prevents distribution of several dozen
known viruses, although, it can also make some difficulties for anti-virus
software in repairing infected files. So, if your anti-virus tells that
the JAM drive is write-protected, while you can copy and/or delete files on
it, you should enable [DirectWrite] mode (using JMOUNT /WD) and rerun anti-
virus again.

5.4. Stacker and other disk compressors

We DO NOT RECOMMEND you use the JAM with other disk compressors (like
Stacker, SuperStor, etc.) simultaneously. Nevertheless, you can install
the JAM on a machine with Stacker, SuperStor, DoubleSpace, or some other
real-time compression program, and run it for evaluation purpose.

The main requirements here are:

* load the JAM.SYS device driver BEFORE the Stacker's or SuperStor's

* use JSWAP utility to reassign your drive letters back (since JAM.SYS
must be loaded first, it occupies the first available drive letter
which can be assigned to a Stacker drive)

* create JAM archive files only on UNCOMPRESSED hard disk drives
(and vice-versa do not create Stac'ed drives over the JAM ones).

* try to avoid reaching the space limits on your compressed drives by
frequently checking its free space.

5.5. Networks

The drive letters used by the JAM for the logical drives are determined by
DOS. When DOS initializes JAM.SYS during the processing of CONFIG.SYS, it
informs the JAM of the next available drive letter. JAM.SYS reports to DOS
the number of drives it controls. DOS then knows what drive letter to
assign to the next block device driver it processes. You can change the
drive letters used by the JAM by installing JSWAP utility (see also section
7.2 below) or (if you have other block device drivers in your CONFIG.SYS
file) by moving JAM.SYS around in the CONFIG.SYS file. The JAM displays the
drive letters it uses on the screen every time the computer is powered up.

Some networks assign their drives to drive letters in a non-standard way.
If there is a conflict between a drive letter used by the JAM and one used
by a network drive, one drive or the other will be unavailable. The only
solution in the present time (other than that mentioned above) is to
reconfigure the network drive to use a letter that doesn't conflict with
the JAM. No data will be lost on the logical drive even if it is
temporarily unavailable due to a lettering conflict.

5.6. Disk repairing/defragmentation utilities

We DO NOT recommend you use standard low-level disk repairing/
defragmentation utilities like Gazelle Systems' OPTune, Norton Utilities'
SPEEDISK (MS-DOS 6.0+ DEFRAG), Central Point Software's COMPRESS, and alike
on a JAM drive.

The JAM has a JCHKDSK disk-repairing utility and JMAX optimizer that are
specifically designed for the JAM compressed data. Commercial defragmenters
will NOT produce a well organized compressed disk, and in some cases
actually DAMAGE the compressed data.

There is nothing wrong however, with running your commercial defragmenter
(or disk maintenance utility) over a disk that is not controlled by
the JAM.SYS.

5.7. Disk Cache utilities

The JAM is fully compatible with almost all standard disk cache utilities
(including HyperDisk, Super PC-Kwik (or its OEM: PC-Cache and Qualitas
Qcache), COMBI-Disk, etc.) which use INT 13h interface only.

Some modern disk caches (like SMARTdrive 4.0+, NCACHE2, NWCACHE, etc.)
intercept (and/or reorganize) requests to all (existing at the moment
of the cache initialization) DOS block device drivers, including the
JAM ones. This means, that the data on the JAM drives would be cached

1. When DOS reads Original Data from/ writes to a JAM drive,

2. When JAM driver reads Compressed Data from/ writes to a
Host drive for the JAM Archive.

To prevent this effect (and to make work with your compressed data
more reliable) you must load your disk cache BEFORE JAM.SYS driver,
thus leaving only the second way for caching JAM drives.

We have made only one exception for the SMARTdrive utility (i.e. built
into JAM.SYS code which automatically reloads SMARTdrive under the JAM
driver), since it cannot be loaded as a disk cache prior the JAM.SYS in

5.8. Data encryption software

There are three main kinds of security programs:

* First (like DR/Novell-DOS LOGIN and PASSWORD commands, MITAC's Advanced
Disk Manager, passwords in FastBack, etc.) offer "password protection
security" which don't perform any encryption, but simply do a password
check to allow access to the data.

There is no any restriction on using such programs with the JAM.
You should only keep in mind, that if your JAM archive file is located
on a password-protected drive/or directory, you should make this place
accessible when JMOUNT will work.

* Second (like Unix's Crypt, Norton Utilities' Diskreet, Central Point
Software's PC-SECURE, encryption features of Arc, Arj, Lotus 123, Lotus
Symphony, Microsoft Excel, Microsoft Mail, Microsoft Word, Paradox,
Pkzip, etc.) can encrypt individual files, so that you (or someone
else) cannot view their original contents.

Such encrypted files (in most cases) are not compressible and will be
stored in uncompressed form, even if you store such files on a JAM
compressed drive.

You might want to store incompressible files on an uncompressed
drive rather than on a JAM drive. Doing so can sometimes improve
your system's speed.

* Third (like Peter Gutmann's SFS) will create a secure disk (encrypted
diskette or whole hard disk partition), which cannot be accessed except
with a password.

JAM is fully compatible with such programs. Moreover using the JAM over
SFS-encrypted disk you can improve security and speed-up the disk
access. To mount a JAM archive located on an encrypted SFS drive you
should add /MR switch to the JMOUNT.COM command line.

5.9 Windows 3.xx

The JAM 1.19 is fully compatible with Windows 3.0, Windows 3.1, W4WG,
and Windows 3.11. Some detailed information about hints in using it with
the JAM drives is given below.

1. If you are installing Microsoft Windows 3.1 onto a JAM drive, we
suggest you take the following course of action while in the Windows
3.1 Setup program;

a. When given the option of which installation mode to use,
select the:

"Custom Setup" option versus the "Express Setup" option.

b. When you are prompted for the path to Windows install, use a
fully qualified path such as; "C:\WINDOWS" or "C:\WIN31".

2. If you use Microsoft Windows 3.x on your PC, and want to move it
on the JAM drive, you should use the JSWAP utility to swap the
JAM drive letter with that on which Windows is currently located.

3. The Windows 3.X Permanent Swap File cannot reside on the JAM drive.
If your permanent swap file is on the JAM drive, Windows can displays
the message "The permanent swap file is corrupt" when it starts.

To move your permanent swap file to an uncompressed drive:

a. Start Windows.

b. At the "Permanent swap file is corrupt" screen, type Y in response
to the question "Do you want to delete this swap file?", and
then press ENTER.

c. Open Control Panel, and then double-click the 386 Enhanced icon.

d. Choose the Virtual Memory button. Windows displays a dialog box
stating that a corrupt swap file was found and asks if you want to
set the file's length to zero.

e. Choose the Yes button. Windows displays another Virtual Memory
dialog box.

f. Choose the Change button. Windows displays swap-file settings.

g. In the Drive list box, select a drive that is not compressed.
In the Type list box, select "Permanent."

When you have finished specifying swap-file settings, choose OK twice,
and follow the instructions on your screen.

4. The following command must be added to the file SYSTEM.INI (in the
[386Enh] section):


6. Possible problems

6.1. JMOUNT displays the message "Archive file is too fragmented"

The JAM is able to handle Archive Files which consist of up to 16 separate
contiguous areas (fragments) upon the Host Drive. A file that resides in
many such separate areas is said to be Fragmented. Large Archive Files
might to be too fragmented for the JAM to handle, and therefore require
special treatment.

Run a disk defragmentation utility (e.g. Gazelle Systems' OPTune, Norton
Utilities' SPEEDISK (MS-DOS 6.0+ DEFRAG), Central Point Software's
COMPRESS, and alike) on your Host Drive, and then rerun JMOUNT.

NOTE: Such utilities usually do not work with DOS files that have the
"Hidden" attribute. Therefore, you must first remove the "Hidden" attribute
from the JAM files. You should then use the utility program to reorganize
the Host Drive, and once again assign the "Hidden" attribute to the JAM
files. Having done so, IMMEDIATELY REBOOT the computer system.

6.2. Some of your programs tell that JAM drive is write-protected

You may receive such message under one of the following circumstances:

1. There is an error in JAM drive data structure, and JAM.SYS has
switched drive in read-only mode (to minimize the data corruption).

Run JCHKDSK /T on your JAM drive. If JCHKDSK will find any error,
follow the steps described in Section 4.5. of the JAM User's Guide.

2. You use some incompatible Device driver or TSR program, which is
loaded over the JAM.SYS driver and call it directly (i.e. bypassing
DOS kernel). For instance, we have detected such situation with:

a) NCACHE2 and NWCACHE disk caches, running over the JAM drive;

b) Stacker and others disk-compressors, which compressed volume
files were located on a JAM drive;

c) the "Dir", and several other computer viruses.

Try to disable each of your TSR program and device drivers (except
the JAM one), and investigate this problem again. If doing so, you
will find a program which conflicts with the JAM driver, try (if it
is possible) to load it before the JAM.SYS device driver in your

3. Your program uses direct disk access.

Some low-level disk utilities (e.g. Norton Utilities' DiskEdit,
DiskTools, UnErase, SpeeDisk, etc.), use direct disk access (DOS
interrupt #26h, direct requests to device driver, etc.) to perform
non-standard activities like file UnDelete operations, reorganization
files on disk, and so on.

To enable direct write operations on the JAM drive, you should use
JMOUNT utility. For more information about JMOUNT utility and the JAM
[DirectWrite] mode read Section 4.5. of the JAM User's Guide.

6.3. You find that your JAM drive mounting as a read-only disk.

A serious error in the JAM archive file structure was detected. To minimize
the data loss, the following steps should be taken:

1. Run JCHKDSK /T on the JAM drive.

2. Analyze the list of errors produced by JCHKDSK.
a) Select all clusters which cannot be expanded.
b) Select files which have these non-expandable clusters.
c) Copy these files on any other drive, by DOS COPY command
On all messages like:
'Unable to read data from drive x: (Abort,Ignore,Fail)?'
answer 'I'- ignore.

3. Run JCHKDSK /T /F again. On all messages like:
'Cluster #yyyyy (file 'xxxxxxxxxx') cannot be expanded, Clear it [Y/N]?
answer 'Y' - clear.

4. Run JMOUNT /U /W to switch the drive in read-write mode.

5. Replace all files which you have corrected by their copies.

7. Addendum to the JAM User's Guide

This section provides some important information which is not included in
the JAM User's Guide.

7.1. The JSIZE utility

Enlarges or reduces the size of a JAM archive file. You might want to
enlarge a JAM drive if its host drive contains plenty of free space.
You might want to reduce the size of a JAM drive if you need more free
space on the host drive.


JSIZE [d:][\][path\]filename[.ext] [+|-][size]


Full or relative path of the JAM archive file. This is optional part
of the name of file to resize. If you omit it, JSIZE uses current
DOS drive/directory to find the archive file.

Specifies the name of the JAM file you want to resize. If you omit
the filename extension, JSIZE uses ".JAM".


Specifies amount of space (in K-bytes) on which the JAM archive
file should be extended (+ prefix), or shrunk (- prefix).
If size not specified, maximum possible value is used.


Before you run JSIZE ...

The JSIZE utility may be run only on Inactive JAM Archive files. Use the
JMOUNT utility to dismount the Archive file, run JSIZE to extend or
shrink its size, and then mount it again.

Also, it is strongly recommended TO TEST AND DEFRAGMENT your disk
BEFORE you extend any archive file. By doing so you will avoid numerous
possible problems, and ensure maximum performance of a JAM drive you
will extend.

Show file size limits

If you run JSIZE without specifying + or - switches, it displays file's
physical and logical capacity for three possible types of configuration:
Minimum (fully shrunk archive), Actual, and Maximum (extended on all
currently available space on host drive).


To show on which size the file C:\TEST1.JAM can be extended (or
shrunk), type the following command:


To extend the size of file C:\TEST2.JAM on 20M, type the following

JSIZE C:\TEST2 +20480

To shrink the size of file C:\TEST3.JAM on 10M, type the following

JSIZE C:\TEST3 -10240

To change the size of file C:\TEST4.JAM so that it is as large as
possible, type the following command:


Error messages

1. Incorrect DOS version.
PC-DOS/MS-DOS 3.30 - 7.0, DR-DOS 6.0, or Novell DOS 7 required.

2. xxxxxxxxx has been detected.
JSWAP cannot run in a multitasking environment.

One of the following multitasking programs (xxxxxxxxx)
is running :
Windows 3.xx in Enhanced mode
Windows 3.0 in Real or Standard mode
MS-DOS Task Switcher
DR-DOS 6.0 TaskMAX
Novell DOS 7 Task Manager

Please exit your task switcher and run JSIZE from the DOS command line.

3. Invalid switch: xxxxx
4. Incorrect parameter: xxxxxx

Specified switch is not supported by JSIZE utility. Run JSIZE /?
for help.

5. Invalid (or DOS reserved) file name: xxxxxxxxxxxx

Specified filename cannot be resolved to fully qualified form
(drive:\path\filename.ext). You may receive this message if
specified drive does not exist, path\filename was spelled
incorrectly, or if you have specified some DOS reserved name
(for example, PRN, CON, NUL, CLOCK$ ...).

6. File xxxxxxxxxxx not found.
7. Name of the JAM file expected.

Name of the JAM archive file was omitted or spelled incorrectly.
To change the size of a JAM drive, you should specify its Archive
File as an essential parameter.

8. Cannot resize a JAM archive located on a network device.
9. Incompatible sector size on drive x:
10. Cannot open file: xxxxxxxxxxxx
11. Cannot read initial sector(s) of xxxxxxxxxxxxx
12. File xxxxxxxxxxx is not a JAM archive.
13. Incompatible JAM file version.
14. Invalid boot record in JAM file xxxxxxxxxxxxx
15. JAM file size/boot record parameters mismatch.

See JMOUNT errors #21-28 for comments.

16. Not enough memory.

Not enough memory to read and analyze archive file structures
(JSIZE tries to keep in memory FAT, JDT, and some additional
tables). For example, to analyze the maximum possible JAM archive
(512M bytes of logical space) JSIZE will need approximately 384K
bytes of conventional memory.).

17. Cluster #xxxx has not been deleted
18. Clusters #xxxx and #yyyy have the same FAT value
19. Cluster #xxxx has not been undeleted
20. Cluster #xxxx has invalid size
21. Cluster #xxxx has invalid location
22. Cluster #xxxx is a compressed subdirectory
23. Cluster #xxxx compressed by unknown method
24. Overlapped clusters #xxxx and #yyyy
25. Cluster #xxxx has incorrect FAT value
26. Data integrity error. Cluster #xxxx cannot be expanded.

Allocation errors were detected on a JAM drive.
Run JCHKDSK /F /T on drive x: first.
See also JCHKDSK errors #33-45 for comments.

27. Incorrect JAM.SYS version.

28. JAM file xxxxxxxxx mounted as drive y:
Please, deactivate this file (type JMOUNT /D y:), and then rerun JSIZE.

29. File xxxxxxxxxx can be extended only on yyyyyyK bytes.
30. File xxxxxxxxxx cannot be extended.
31. File xxxxxxxxxx can be shrunk only on yyyyyyK bytes.
32. File xxxxxxxxxx cannot be shrunk.

Specified [+|-]size parameter is out of range, or file cannot be
extended (shrunk) any more.

33. Cannot change current position in file: xxxxxxxxxxxxx
34. Cannot modify file: xxxxxxxxxxxxx
35. Cannot close file: xxxxxxxxxxxxx
36. Cannot change file attributes.
37. Cannot extend file. Trying alternate method ...
38. Cannot shrink file. Trying alternate method ...

A file I/O error has occurred. In all cases, when DOS fails to
continue operation, JSIZE tries to analyze information on host
drive manually (bypassing DOS), and finishes this action, or,
if it is impossible -- makes undo changes.

7.2. The JSWAP utility

JSWAP lets you switch between the names of any two drives.

For example, entering


will switch the names of drives C: and D:, resulting in drive C: effec-
tively being mapped to the original drive D:, and drive C: effectively
being mapped to the original drive D:.

Using the JSWAP utility might be of utmost importance for users whose
applications and batch files are "tailored" to use a specific physical
drive letter (most often C:), which would have to be reconfigured to work
with a different drive letter if moved to work with a JAM drive letter
(e.g. D:).

Instead of going through the tedious process of reconfiguration, you may
just use the 'JSWAP C: D:' command to switch between the names of C: (the
original drive letter) and D: (JAM drive-letter). Now you can just use your
JAM drive as drive C: with all your preconfigured applications and batch
files as before!


JSWAP [/Q] d1: d2:
DEVICE=[drive:][\][path\]JSWAP.COM [/Q] d1: d2:


d1: d2:
Drive letters to interchange. Any drive letters, which are assigned to
existing DOS block devices, should be specified.

Specifies the location of the JSWAP.COM file.


Quiet mode (does not display status messages).

/? or /H
Displays online help screen.

Error messages

1. Incorrect DOS version.
PC-DOS/MS-DOS 3.30 - 7.0, DR-DOS 6.0, or Novell DOS 7 required.

2. xxxxxxxxx has been detected.
JSWAP cannot run in a multitasking environment.

One of the following multitasking programs (xxxxxxxxxxxx)
is running :
Windows 3.xx in Enhanced mode
Windows 3.0 in Real or Standard mode
MS-DOS Task Switcher
DR-DOS 6.0 TaskMAX
Novell DOS 7 Task Manager

Please exit your task switcher and run JSWAP from the DOS command line.

3. Cannot locate DOS CDS array.

Some control programs (like DR-DOS 3.31+) do not initialize pointer to
the DOS CDS array, during loading device drivers. To avoid this
problem, run JSWAP.COM program from your AUTOEXEC.BAT instead.

4. Cannot swap drives. DOS FASTOPEN installed.

5. Cannot swap drives. Invalid drive specification X:

6. Cannot swap drives. Open files on drive X:

Close all files on drive X: and run JSWAP again.

7. Cannot swap drives. Drive X: is a network drive.
8. Cannot swap drives. Drive X: is a JOINed drive.
9. Cannot swap drives. Drive X: is a SUBSTed drive.
10. Cannot swap drives. Drive X: is an ASSIGNed drive.
11. Cannot swap drives. Drive X: is a phantom drive.

JSWAP cannot interchange drive letters of non-physical DOS drives.
In most of these cases, you could simply change the letter which is
used to create a JOINed, ASSIGNed, or SUBSTituted drive.

12. Drives should be different.

JSWAP cannot interchange the drive letter with itself.

7.3. The JCMD utility

Replaces standard DOS "DIR" and "CHKDSK" commands by JDIR
and JCHKDSK programs.


JCMD [/I | /R] [drive:][\][pathname]


Specifies the location of JDIR.COM and JCHKDSK.COM programs.
If not specified, current disk/directory is used.


Install JAM interceptor
Remove JAM interceptor from memory

Error messages

1. Incorrect DOS version.
PC-DOS/MS-DOS 3.30 - 7.0, DR-DOS 6.0, or Novell DOS 7 required.

2. JCMD already installed.

3. JCMD is not installed.

4. JCMD cannot be removed.

JCMD cannot be removed from memory due to another TSR program,
loaded after JCMD.

5. File search error.

Either specified drive does not exist, or drive\pathname was
spelled incorrectly.

6. File xxxxxxxxxxxxx not found.

Either JDIR.COM or JCHKDSK.COM does not exist in specified
(current) directory.

8. Technical support

We hope that your use of the JAM will be enjoyable and trouble-free.
It is our intention to provide the best possible product and documentation.
We understand that problems may arise, and in most cases you will be able
to resolve any problems you may have by referring to the documentation.
Answers to questions you might have will usually be found within pages of
the JAM User's Guide.

If you find that you need technical support you can send your requests

JAM Software
George A. Reznik Internet: [email protected] (the best way)
Vasilkovskaya str.8, apt.139 [email protected]
252040 Kiev, UKRAINE

Voice: +7(044) 266-6547 Monday through Friday,
6 pm to 10pm Kiev Time (+7 hours GMT)
FAX: +7(044) 266-4091 Monday through Friday,
9 am to 5 pm Kiev Time (+7 hours GMT)
BBS: +7(044) 266-6547 without weekends
11pm to 7 am Kiev Time (+7 hours GMT).

We will be happy to help you with problems and answer your questions.
We would also like to hear any suggestions you have for how the JAM
can be improved.

 December 14, 2017  Add comments

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