20uS is doable (UPURS manages 8->9uS through some clever code unwrapping and cycle counting; MartinB and hoglet get the kudos for that!).the timing looks to be around 20us or so
It's easy enough to count clock cycles (eg from the table https://www.masswerk.at/6502/6502_instruction_set.html).
Remember that at 2Mhz it's 2 clocks per uS, but when access the 1Mhz bus (User port) the clock is stretched. So "LDA &FE60" is effectively 6 cycles whereas "LDA abs" is normally 4 cycles. You might find some strategic NOPs (2 cycles) are all you need to get to 20uS
Statistics: Posted by sweh — Thu May 08, 2025 8:33 pm