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Both run on 6502 processors.
Code #1 is a delay loop. Code #2 is a 16 bit unsigned multiply (multiplies $20/$21 by $22/$23, returning the result in $24/$25/$26/$27). Update: OK, I couldn't resist. I dug out the 6502 assembler and emulator to test code #2. Now, admittedly, the emulator could be broken, but I didn't get any results that made sense for either a multiply or divide. I spent about 45 minutes playing with this, and the simulator seems to be executing as I would expect. But the resulting $26/$27 locations never come up with any valid values using $20/$21 and $22/$23 as inputs (the higher address is the high byte of each word, so I had byte ordering correct). And since code #1 was going for maximum delay, you could have gotten a little more delay by changing it to: start LDY #$FF loop1 LDX #$FF loop2 DEX BNE loop2 DEY BNE loop2 RTSYou're resetting X to #$FF, when it's already 0, losing 255 free 2 cycle delays. --Chris In reply to (jcwren) RE: (2) What was your first program?
by jcwren
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