toinet
Inscrit le: 15 Juin 2007
Messages: 326
Localisation: Paris, France
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 Post� le: Lun 06 Ao� 2007, 11:49 Sujet du message: Ikari Warriors (Data East, 1987) |
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Defeat your ennemies, drive tanks, drop grenades. The fate of the world is within your hands... Really nice double-sided game, ported to the Apple II by Quicksilver Software, well-known for their QuickDos loader and their poor protection scheme...
PROTECTION TYPE
- Disk protection (D5 AA 96, end of header markers not used, D5 AA AD, end of data headers not used)
- Desynchro routine (just like the Epyx ones)
REMOVING THE DISK PROTECTION
- Launch Advanced Demuffin
- Copy the disk with the following markers: D5 AA 96, FF FF, D5 AA AD, FF FF)
That's it...
REMOVING THE DESYNCHRO PROTECTION
The QuickDos is loaded at $D200 and the protection routine is at $D800. It checks for the usual FC EE EE E7 markers on the disk. If that fails, the memory is cleared and the disk is rebooted.
Search for the $D800 hexa string with your favorite sector editor, you will find one on BOTH sides on track 0, sector 3. The code is the following:
| Code: | JSR $D800
BCC *+3
JMP rebootNow |
The code at $D800 returns with the carry clear is the FC EE EE E7... pattern is found, otherwise the carry is set.
Now that you master sector editing, I will let you choose the way to remove the protection:
1/ Put NOP (EA) in place of the code above
2/ Put CLC RTS (18 60) at $D800
3/ What I have done is replace the JMP (4C) with the BIT opcode (2C) on the above code. I will check whether it is emulator compatible...
Regards,
Antoine |
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