HOW TO UNPROTECT MICROCAD, by Computer Aided Design

First, make a copy of the original distribution disk. NEVER mess with the
original diskette, unless you like blowing your software away...

MicroCad is well-protected, with a variety of slimy and disgusting tricks
which the authors THOUGHT would stop us. (They make extensive use of
self-modifying code which "decodes" itself just before it executes.) But WE
know better, don't we?  We will need to make extensive changes with a
good disk zap utility such as the Norton Utilities.  In the instructions
which follow, all bytes are in hex:

(FM included on this disk will work fine - Public Brand Software)


Search the file MICROCAD.EXE for the following byte strings and make
the changes shown. Be SURE to write the changed bytes to disk as you
make them!

Search for:   FA 0E 1F B9 07 00 33 FF
Change to :   FA 0E 1F B9 00 00 EB 0C   (skip low mem clobber!)

Search for:   33 FF 26 8A 05 03 D8 30 85 EA 04 86 85 68 04 AA E2 F0
Change to :   BF 68 04 8A 05 03 D8 30 85 82 00 90 90 90 90 AA E2 F1
(Decode next code segment without funny business!)

Search for:   3A B9 69 03 D6 B1
Change to :   D2 6A 6A 50 34 56 D4 A1 6A EA E3 03
(Encode some pushes, make BP get proper value, and branch around
 diskette checks)

NOTE: The third change above is longer than the search string because the
search string is used only to locate the proper point in the code. Just keep
changing bytes after the "B1" byte and don't worry about what values they
have.

After these changes are made and written to the disk, MICROCAD is fully
unprotected, and may be run from a hard disk, ram disk, or copied to a
floppy.  HOWEVER, during execution, Microcad reads some files from disk
and ASSUMES drive A.  This means that for transparent operation from a
hard disk (drive C, say) you must do an ASSIGN A=C before running the
unprotected version of MICROCAD.  Messy, what? I thought assuming
drive A: went out with DOS 1.1...

So anyway:



LET THERE BE SOFTWARE!