How to Unprotect Chuck Yeager's Advanced Flight Simulator

                        How to Unprotect Chuck Yeager's
                          Advanced Flight Simulator
                                version 1.0



     This program uses a rather simple protection scheme to prevent
you from making usable backups or installing it on a hard drive. The
program allows you to make as many copies as you want from the master,
however the master disk must be in drive A to use those copies. This
unprotect shows how to bypass that feature.

     Because the program always looks to the master for verification,
I scanned the entire disk using Norton's NU program, and found track
15 was marked as BAD. After some investigation, it looks as though
that track was formatted as having over 100 sectors!! Unable to
reproduce that formatting scheme on my backup disk, I disassembled
the AFS.EXE file and found the following code (comments and labels are
mine):

 E8 0B 00                CALL    0AB8            ; Check copy protect
 3C 00                   CMP     AL,0            ; if al = 0 it's a master
 74 06                   JZ      OK
 BE 53 05                MOV     SI,OFFSET 0553  ; else print "No key disk"
 E9 0C A7                JMP     BAD
                OK:      RET       


     As a fluke it tryed just NOP'ing the comparision code out, and
lo and behold it worked!! Total time to unprotect, 45 minutes.


        How to unprotect:

        1) Copy master disk using diskccopy. Do the following changes
           on that copy, NOT the master (just in case).

        2) Using Norton's NU or similar, in AFS.EXE, search for the
           entire HEX string or smaller portions of:

                         EB 0B 00 3C 00 74 06 BE 53 05 E9 0C A7

        3) Set the following HEX bytes to 00 (NOP):

                         3C 00 74 06 BE 53 05 E9 0C A7

        4) Write changes and exit.


     When AFS boots, it will no longer read drive A and may be copied
     using DISKCOPY.


                                Another Hack from,
                                         The Mole.      :)