Spiele mit illegal opcodes
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Hier steht etwas über "Ultima":
ZitatThere has been a long standing bug in the original, BASIC version of
Ultima that made it impossible to hit the alien ships to become a
Space Ace. I was able to isolate the problem routine and posted to
comp.sys.apple2.programmer for help. Rubywand
figured out the problem and provided a patch.The problem was in a small machine routine that used and undocumented
6502 opcode that a 65c02 would not recognize. However, here's the
fix;(Boot a AppleDOS 3.3 diskette and then load the Ultima Boot diskette)
]UNLOCK FGT3
]BLOAD FGT3
]CALL-151
*74D1:46 43 45 43
*3D0G
]BSAVE FGT3,$A7400,L$120
]LOCK FGT3(Reboot and away you go)
I tried it and it works beautifully!
Kann mir da mal jemand unter die Arme greifen und den obigen Patch erklären? Insbesondere interessiert mich, welche (illegalen) Opcodes da vorher im RAM waren und durch welche sie ausgetauscht werden.
Danke!
µP