4 ms·
I believe the undocumented instructions in the 6502 was caused by race conditions in the CPU. Some of these instructions are actually usable while others give r
by lokedhs 7y ago
I believe the undocumented instructions in the 6502 was caused by race conditions in the CPU. Some of these instructions are actually usable while others give random results.
- jacquesm 7y agoI wrote a 6502 assembler and had a really hard time not giving $88 it's own mnemonic in the main table rather than to load it at the start of every file from an include. It was just too useful :)
- lokedhs 7y agoWhy wouldn't you? These opcodes seems to be used by most people these days, so there seems to be no reason not to treat them just like any other opcode?
- mondoshawan 7y agoAh, no. Those are caused by don't care states in the logic of the PLA instruction decode block.