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Space Quest unprotect. by Independent (IND)

89 of 565 files independent
3 items
  • LARRY.DAT
  • SIERRA.DAT
  • SIERRA.DOC
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This procedure will enable you to unprotect Sierra On-Line's SPACE
QUEST game.  The procedure is based on an unprotect procedure for
KING'S QUEST III, by an unknown author.
Also Sierra's LEISURE SUIT LARRY. (Added by a third author...me.)

There are three files included in this ARC package:

1.  SIERRA.DOC - This file
2.  SIERRA.DAT - Supplementary file needed during DEBUG session.
3.  LARRY.DAT - Supplementary file needed for LEISURE SUIT LARRY. 

SIERRA.DAT was originally named KQ3MERG.DAT, but I've taken the
liberty of renaming it, since it is usable in other Sierra games.

The procedure is relatively simple:  

1) Put a blank, formatted diskette in drive B, and the Spacequest Disk
or Leisure Suit Larry Disk  
#1 in drive A, then at the A> prompt, COPY *.* B:.  Then put Disk #1
away - you won't need it anymore!

2) Load DEBUG, making sure both SIERRA.COM (on the backup disk) and
SIERRA.DAT and or LARRY.DAT (from this package) are both in the current 
path or default drive.

3) Use DEBUG to patch SIERRA.COM

A>DEBUG SIERRA.COM
-N SIERRA.COM
-R                             (Record value of CX register)
-N SIERRA.DAT (LARRY.DAT for Liesure suit Larry) 
-L 141
-E 395 (038d for Larry)     <- Change for other games
XXXX:0395 E8.90 52.90 02.90  (XXXX:038d E8.90 0E.90 04.90  'for Larry') 
-N SIERRA.COM
-R CX
CX 0080
:????                          (Enter value of CX you recorded)
-W
-Q

4) That's all there is to it.  SPACEQUEST or LEISURE SUIT LARRY 
unprotected. 

This procedure will probably work with any Sierra game that uses the
SIERRA.COM game loader.  To check, try the following DEBUG session:

-N SIERRA.COM
-D 100             (You will see a dump of the first part of the
file.  If the version is 3.0, this patch
should work.  If not, you can try, but there
are no guarantees)
-R (Record the value of the CX register)
-S 100 ???? E8 52 02 (Replace ???? with the value of the CX
register)

You're looking for the E8 52 02 string, which is the call to the
protection scheme.  With luck, DEBUG will report only one find. 
Replace the 395 with that location in the above e 395 procedure
and do everything else the same.  The idea is to NOP around the
call.  SIERRA.DAT contains some code that is overlaid on a
section of SIERRA.COM - I don't know how it works, but it does.

Have fun!
ETS
JED (...me)