3 ms·
So does it use any unofficial opcodes for performance? (IIRC, the 6502 decoded instructions by bitmasks; say bit 7 meant "load" and bit 6 meant "move" or some
by jaylevitt 14y ago
So does it use any unofficial opcodes for performance?
(IIRC, the 6502 decoded instructions by bitmasks; say bit 7 meant "load" and bit 6 meant "move" or some such thing. So you could trigger combination instructions that'd still execute in 3 cycles but perform the work of two instructions that'd normally take 6. This might have been 6510-only, but I don't think it was.)
- to3m 14y ago"How MOS 6502 Illegal Opcodes really work": http://www.pagetable.com/?p=39 http://www.pagetable.com/?p=39
- rbanffy 14y agoSadly, the 65C02 used on the //c and //e enhanced converted those to NOPs :-( I actually had to rewrite some code because of that. I remember the comments in the source code were less than kind towards the engineers responsible. I may even have the listings somewhere.