Blush

Overclocking would be as the name describes, upping the clock speed. Not sure how that would work on the Neo Geo. The 30Hz interrupt I mentioned is a lbiurary routine called each time which updates the timekeeping clock, does some bookeeping and reads the inputs.
On this one pinball project I am doing right now, I am doing a similar kind of routine as what is called an event loop. Let me throw you what happs in it and compare it to an arcade game loop.
pinball
init variables
LOOP
read/process all inputs
do game logic (rules)
set up and push outputs
goto LOOP
video
init vairables
LOOP
do game logic(rules)
setup and push video
goto LOOP
during the loop, the 30Hz interrupt will jump out to do the various things mentioned abhove.
For my pinball example up above, I will be creating an interrupt, am just rusty as heck and want to get the bugger going asap

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The interrupt can be set up to the start of the screen draw, so the logic rules ands things would be done when its not draswing onscreen...