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Zip Chip is an accelerator chip for the Apple //. What follows is 6502 assembly language. You have been warned.

To enable maximum acceleration of everything except the joystick port, the Apple speaker, and slot 6:

  LDA   #$5A
  STA   $C05A ; write 4 times to unlock chip
  STA   $C05A
  STA   $C05A
  STA   $C05A
  LDA   #$FF
  STA   $C05B ; enable Zip Chip
  LDA   #$80
  STA   $C05E ; disable I/O delay
  LDA   #$40
  STA   $C05F ; normal joystick speed, fast language card
  LDA   #$41
  STA   $C05C ; all slots fast except S6 and speaker
  LDA   #$00
  STA   $C05D ; CPU at full speed
  LDA   #$A5
  STA   $C05A ; lock chip

To disable all acceleration:

  LDA   #$5A
  STA   $C05A ; write 4 times to unlock chip
  STA   $C05A
  STA   $C05A
  STA   $C05A
  LDA   #$FF
  STA   $C05A ; disable Zip Chip

These routines work on both the Zip Chip 4000 (4 Mhz) and Zip Chip 8000 (8 Mhz).

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