Commodore 64 Audio Question

[Timepilot2084]

Forgive me if I'm posting in the wrong area, I didn't see a Commodore 64 specific thread, but I'm using a stupid tablet and it's possible I overlooked it. I have a question regarding the use of digitized sound effect and speech on the C64. I'm pretty familiar with programming, and have even made several games using BASIC with ML subs, but I can't figure this one out. Why is it that some games can play digitized audio over two voice music without stopping all the on-screen action, but some stop all sprite movement and audio before playing the sample? For instance, Way of the Exploding Fist has no trouble playing the digitized samples during the action. Thanks for reading!

[Rybags]

For digitized playback to work you have to plug the samples very often. Like 4,000 times a second minimum. Decent playback will be 8,000 or more.

 

That's a fair chunk of CPU time and some games will stop all the action. Others use more advanced techniques like Timer interrupts which allow other processes to continue on, but there's still the CPU demand.

 

Earlier games that used it generally had delay loops, not timers - so everything stopped. Once programming tricks got developed a lot started using Timers. So long as the game can put up with that chunk of CPU time being lost and still maintain fluid motion then it's a feasible technique.