If I try to start the first version of the game Karateka for Apple IIe on an Apple IIc, the Apple IIc will restart after reading the game from disk after a few seconds. Later versions of Karateka for Apple IIc will work. What is the bug in the first version that caused it not to work with Apple IIc?

  • 1
    Also consider the possibility that you are using "cracked" versions, which may be faulty, not "first" and "later" versions.
    – dirkt
    Jun 10, 2020 at 10:47
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    Can you please link to a version which doesn't work? IIRC, Karateka used boot zero (the Disk II Interface Card ROM) in a way which caused problems for later boot ROMs in the Laser 128 and Apple IIgs. Jun 10, 2020 at 11:13
  • Version on disk but I think @dirkt is correct, it is cracked version. But it still have some bug cause reset on Apple 2c but not Apple 2e. This is a bug I see many years ago.
    – Châu
    Jun 10, 2020 at 23:48
  • It's possible that it included a check of certain ROM locations which differ between the machines. Choplifter wouldn't boot on a IIe vs II+ for that reason. Jun 12, 2020 at 16:43

1 Answer 1


For the cracked version the problem was identified long ago:

I have heard that it is only the cracked version of Karateka which has a problem.

The problem is that on every disk access, Karateka takes a copy of the ROM from the Disk II controller card and patches it. It then uses the patched copy to do the disk I/O. The resulting code crashes on the IIc and IIgs because the routines in the firmware are in a slightly different location. -- David Empson

The IIgs problem is with the slot 6 "Disk Port" firmware. The problem will not occur if the slot configuration is set to "Your Card" and a Disk II Interface Card is present.

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