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RBBS in a Box Volume 1 #2
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1984-06-18
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PC MAN PATCH
by
Ken Sykes
DISCLAIMER
The patch shown below should only be applied to a backup of your PC MAN
disk. I am not liable for any damage that may be induced from this
patch.
NOTATIONS
The following notations have been used:
T x S y - Track x Sector y (All disk operations use head 0)
$ n - offset of byte in specified sector
L n - logical disk address for DEBUG
THE PATCH
To use these patches, load in the specified sector, move to the offset,
make the change, and save the change. I will first give you the
addresses, then the steps to make mods using three disk editors: DEBUG,
NORTON UTILITIES, and SNOOP (see end of article for description of
SNOOP).
T1S2, $FD - This byte tells PC MAN what screen to start on.
L10 Enter a value from 2-9 (PC MAN) subtracts one from
this location to get the actual starting screen.
T1S2, $F8 - This byte tells PC MAN how many men to start with
L10 each game. Enter a value from 0 to 13, since PC MAN
clutter the screen with men above 13.
All examples below assume two drives, DOS 2.0
Patches using DEBUG
1. Boot DOS
2. Insert disk with DEBUG in drive A, PC MAN in drive B
3. Type DEBUG <enter>
4. Type L CS:0 1 10 1 <enter>
5. To change starting screen:
Type E CS:FD n <enter> (n=starting screen)
To change number of men:
Type E CS:F8 n <enter> (n=number of men)
6. Type W CS:0 1 10 1 <enter>
7. Now boot PC MAN. The changes are now in place.
Patches using NORTON UTILITIES
1. Boot DOS
2. Place NORTON UTILITIES in drive A, PC MAN in drive B
3. Type SM <enter>
4. Press F7
5. Type 1 <enter>
6. Type 2 <enter>
7. move cursor using arrow keys to correct offset (offset shown in
upper right corner). Both of these patches are located near
the center of the screen.
8. make the changes by overtyping the desired values.
9. Press F9 when finished making changes
10. Press F10 to exit SecMod.
11. Boot PC MAN.
Patches using SNOOP (this can run in 1.1 and still make changes)
1. Boot DOS
2. Insert SNOOP in drive A, PCMAN in drive B.
3. Type SNOOP.
4. Press B.
5. Press Y.
6. Hit a key.
7. Press R.
8. Type 1 <enter>.
9. Type 2 <enter>.
10. Press M.
11. enter the offset
12. Press H.
13. enter new value.
14. Press N.
15. Type Y <enter>
16. Press T.
17. Boot PC MAN.
DESCRIPTION OF SNOOP
SNOOP is a Machine Language Disk utility that covers almost all the
functions desired by programmers. This includes reading non-standard
disk formats, locating a string of hex or ascii characters, File and
disk maps, label changing, file attribute changing, etc. The program
is menu driven, runs easily in 64K, and has fast screen I/O. In my
opinion, SNOOP is better than Peter Norton's disk utilities (which were
written in PASCAL). The only major item SNOOP is missing is file
recovery, though corporate rumors tell me file recovery could be in the
next version. In light of its price ($40), SNOOP should be a very cost
effective tool. Anyone interested in ordering SNOOP can write to the
following address:
OTTER CREEK SOFTWARE
75 Hunting Lane
Goode, Va. 24556
FURTHER STUDY
The patches I described just scratch the surface of the things you can
do to PC MAN, and other programs as well. To explore PC MAN further, I
will explain how I found these patches.
First, I loaded in QuadRam's ramdisk program (QM2.EXE) to take
advantage of the reset feature (CTRL-ALT-DEL won't clear memory).
After setting up a 32K print buffer, insert PC MAN and reboot. After
the music stops, insert DOS 1.1 and reboot again.
The screen will be in the Hi-Res mode, so don't be alarmed when no
cursor appears. Enter Debug and press U <enter>. And Behold! Here is
PC MAN in the unprotected form. Now, any experienced assembly language
programmer can trace through the program and find out anything about PC
MAN. Here are some offsets of little tidbits I have found:
CS:6F0 - # of men
CS:2F8F - Controller used : (1=Keyboard, 0=Joystick)
CS:2FA0 - Sound byte (1 on, 0 off)
CS:360 - General area that takes care of decrementing men (I can make
the program not update the number of men on the screen, but
I haven't been able to make an infinite men patch.)
To find the track and sector on the disk, I copied a few bytes
surrounding the desired location and used the locate command in SNOOP
to locate the track/sector/offset.
There are many other possibilities. I would be interested in hearing
from anybody that figures out an infinite man poke, or Placing PC MAN
on a hard disk. They are entirely possible using the programs and
information I have given above. I hope this sparks the curiosity of
fellow hackers.
Ken Sykes
mation I have given above. I ho