Convert Bascia Files to A

 BBS: Inland Empire Archive
Date: 07-05-92 (19:24)             Number: 299
From: MARK BUTLER                  Refer#: NONE
  To: MONTE FERGUSON                Recvd: NO  
Subj: Convert Bascia Files to A      Conf: (2) Quik_Bas
 On 07-01-92 Monte Ferguson wrote to Jeff Taylor...

 JT> I need some help locating a program that will convert a program,
 JT> written in MS-DOS 3.3 Basica, to an ASCII text file so that it
 JT> can be read in Qbasic. A friend of mine showed me his problem
 JT> and I could not believe that a  file written in Basica was
 JT> incrypted in some way.

 MF> BASICA can save files in one of three formats:

 MF> 1) Binary memory image........<text deleted>..............
 MF> 2) Text file.......<text deleted>..................
 MF> 3) "Protected" binary. This is a method of saving the file so
 MF> prying eyes and fingers can't mess with it.
 MF> .......<text deleted>..................

 Some time ago Tom Hammond posted a a patch for GW-Basic that would
 cause it to list any file normally whether it was saved in
 "protected" format or not. You are right, the "BLOAD" method doesn't
 works on some versions. Tom's says his patch works for version 2.0 of
 GW-Basic but I tested this patch out on two later versions of GW-
 Basic (v3.22 and v3.23) and found that it worked with them to. I only
 wish I'd known about this patch five or six years ago! The following
 is an excerpt from Tom's post...

 --------------------------8< CUT HERE  8<----------------------------

 Unprotecting BASICA (or GW Basic) files is a fairly simple task, if
 you have the right tools and know what to look for.  The following
 sequence is the procedure for creating a copy of BASICA, version 2.0,
 that will NOT test the protect flag when you ask for a LIST, LLIST,
 SAVE, etc. This procedure is possible as the BasicA LOAD or implied
 (command line) program load both convert the program to BasicA's
 normal tokenized internal format and just relies on an internal flag
 to disallow those commands.  This patch changes that flag test to
 always return "allowed".

 In the following we patch the main version of BASICA (in this
 version, three programs make up the BASIC set, they are named
 BASIC.COM, BASICA.COM and BASICA.EXE.  The first two are just loaders
 for the latter, which we'll patch).

 Note, finally, that the search pattern I used is for the OR AL,AL JMP
 +2 POPF RET and JMP opcodes, which makes the search version
 independent (where the exact addresses may vary).

 The comments following the "*" character have been added as an

 A> copy basica.exe                * Make an editable copy to
         1 File(s) copied                * (DEBUG won't edit .EXE

 A> DEBUG                          * Invoke DEBUG b.XXX

 -s cs:0 ffff 0a c0 75 02 9d c3 e9       * Search for the test, NO
 786B:A557                               * DEBUG only found the right
 -u cs:a554                              * Now, UNASSEMBLE 3 bytes
                                           BEFORE that.
 786B:A554 A00C06         MOV    AL,[060C]
 786B:A557 0AC0           OR     AL,AL
 786B:A559 7502           JNZ    A55D
 786B:A55B 9D             POPF
 786B:A55C C3             RET
 786B:A55D E95068         JMP    0DB0
 786B:A560 807C2800       CMP    Byte Ptr [SI+28],00
 786B:A564 7403           JZ     A569
                                         * NOTE in the above that the
                                         * address of the first
                                         * instruction may vary slightly
                                         * with the BASICA version.
 -a cs:a554                              * ASSEMBLE the following patch:
 786B:A554 mov al,0                      *   Put a zero into AL,
 786B:A556 nop                           *   NOP for the correct code
 786B:A557                               * RETURN only to stop ASSEMBLE.
 -u cs:a554                              * UNASSEMBLE the code to check
 786B:A554 B000           MOV    AL,00
 786B:A556 90             NOP
 786B:A557 0AC0           OR     AL,AL
 786B:A559 7502           JNZ    A55D
 786B:A55B 9D             POPF
 786B:A55C C3             RET
 786B:A55D E95068         JMP    0DB0
 786B:A560 807C2800       CMP    Byte Ptr [SI+28],00
 -w                                      * Looks good, WRITE it to disk,
 Writing FF90 bytes                      * this may vary slightly on
                                         * yours,
 -q                                      * and QUIT the DEBUG.

 A> Ren b-unprot.exe               * REName the file to use it.

 That does it.  You now have a program named B-UnProt that will allow
 you to LOAD a protected file and then LIST, SAVE, edit, etc, it to your
 heart's content.
 --------------------------8< CUT HERE  8<----------------------------

 Well, that's it. Work's like a charm to!

 -----------> MHB :-)

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