Hi Jason,
> I've put in what
> I *think* the cycle counts are for this little snippet
> of the code - could somebody just verify it for me so
> I know if I'm on track or if I've missed something?
You have the right idea but some of your opcode timing values are off. Look at http://www.6502.org/tutorials/6502opcodes.htm for a list of opcodes and the time it takes to execute them.
> LDA PF0Data,X ;[10] 5
The above instruction will take 4 cycles if the table look up doesn't cross a page boundary.
> CPY LanderYPos ;[29] 4
This is ZP, right? Then it will take 3 cycles
> LDA LanderHeight ;[35] 4
> STA LanderVisible ;[39] 4
These would take 3 cycles
> LDX LanderVisible ;[36] or [43] 4
3 cycles here
> DEC LanderVisible ;[54] or [62] 6
5 cycles here
I hope this helps.
Take care,
Dennis
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