Breaking the DRM on the 1982 Apple ][+ port of Burger Time


4AM is a prolific computer historian whose practice involves cracking the copy protection on neglected Apple ][+ floppy disks, producing not just games, but voluminous logs that reveal the secret history of the cat-and-mouse between crackers and publishers.

4AM's logfile for their crack of the 1982 crack of Burger Time (which I played until my fingers bled, but on a Colecovision, I think) reveals some incredible, subtle trickery that played out within the extremely confined headroom of a 5.25" floppy's limited sectors.

Chapter 1
In Which We Start From Scratch

We're starting from bare metal on this
one. My automated tools, they do nothing
for us. Strap in.

[S6,D1=original disk]

[S6,D2=crack-in-progress (the partial
  copy I made with Locksmith Fast Disk

[S5,D1=my work disk]

]CALL -151


; copy boot sector (T00,S00) to the
; graphics page so it survives a reboot
96F8- A0 00 LDY #$00
96FA- B9 00 08 LDA $0800,Y
96FD- 99 00 20 STA $2000,Y
9700- C8 INY
9701- D0 F7 BNE $96FA

; turn off slot 6 drive motor
9703- AD E8 C0 LDA $C0E8

; reboot to my work disk in slot 5
9706- 4C 00 C5 JMP $C500

BurgerTime: A 4am crack, 2015-12-31 [4AM/]

Apple II Library: The 4am Collection []

(via JWZ)

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