[Coco] Copy Protection

[Gene Heskett]

On Monday 28 June 2010, Steve Ostrom wrote:
>I good friend of mine sent me a few disks that had some really great
>programs on the disks.  These programs are normally copy protected, but
> all had the same scheme.  If you type DIR, the directory is displayed but
> there is also a title header in place of the first 10 or so lines of the
> directory.  This title was not spaced as if they were disk entries, but
> looked just like a center-justified word processing document.  Very neat.
>
>One of the files on the disk was named "*".  It contained a series of
> pokes that created a small ML program.  These same pokes were used for
> all of the disks, no matter if they were Cer-Comp or Game Point Software.
>  I hand-disassembled the code - see below.  I'm a bit rusty at this, but
> I think that what I disassembled is close to accurate.  Here is the code,
> which is poked into address $01D1.  I asssume this is the area of BASIC
> that is hooked to auto start.  Can anyone tell me exactly what is being
> done by this code?  Did I make any really bad disassembly blunders?  I
> can't believe that this snipit really defeats copy protection.  Also, one
> of the disks was definitely unprotected by Defeater by Carl England, but
> only one.  The rest used this scheme discussed above.  Ideas???:
>
>   86   LDA#22
>   22
>   8E   LDX#2600
>   26
>   00
>   8D   BSR #0D   -->A
>   0D
>   FC   LDD $2600
>   26
>   00
>   10   CMPD #4F53  if # is $, then make this ascii, I think its 'DI'
>   83
>   4F
>   53
>   26   BNE #03   -->E
>   03
>   7E   JMP $2602
>   26
>   02
>E 39   RTS
>A 34   PSHS #2010
>   20
>   10
>   BE   LDX $C006
>   C0
>   06
>   A7   STA 2,Y
>   22
>   86   LDA #02
>   02
>   A7   STA ,Y
>   A4
>   6F   CLR 1,Y
>   21
>   6F   CLR 3,Y
>   23
>   6C   INC 3,Y
>   23
>   AF   STX 4,Y
>   24
>D 10   LDY $C006
>   BE
>   C0
>   06
>   A6   LDA 3,Y
>   23
>   81   CMPA #13
>   13
>   27   BEQ #12   -->B
>   12
>   AD   JSR [$C004]
>   9F
>   C0
>   04
>   4D   TST A
>   27   BEQ #06   -->C
>   06
>   6C   INC 3,Y
>   23
>   6C   INC 4,Y
>   24
>   20   BRA #E9   -->D
>   E9
>C 7F   CLR $FF40
>   FF
>   40
>   35   PULS #A0
>   A0
>B 4F   CLR A
>  20   BRA #F8   -->C
>   F8
>
>
>
>
>Thanks!!
>
>-- Steve --
>
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>


-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
By trying we can easily learn to endure adversity.  Another man's, I mean.
		-- Mark Twain