Append to RE[1]: Audio capabilities


Audio capabilities


Just my personal opinion on this, if I am not boring enough already: I'm not sure if there will be DMA-like stuff for that. I also had that thought, but honestly, it's kinda interesting that it worth at all, if you have 50MHz CPU as well ... Just think about that, the famous GLX player on IBM XT @4.77MHz could achieve playing something like 20 channel module playback or so? :-O Yeah, I guess it used SoundBlaster's DMA anyway too, to play the mixed sample, but still, compare the raw CPU power then. What I found more useful is to have a FIFO so you can "inject" some amount of samples quickly (btw even using the DMAgic of M65 ...) and it can have a full/empty (and especially almost/half empty for example) signals. A dedicated sound DMA is - I guess - more complicated and maybe not so much 8 bit-ish already at all, if I can say that. Even this is a bit that. I guess M65 can happily use just an IRQ or something at the given sample rate to send data and still has enough CPU power left for the work. Some time ago I wrote an SD-card audio play running on 4MHz Z80 (and Z80 has worse IPC than 65xx CPUs) and it was capable to play at around 30KHz, still having enough CPU time to send control to the SD-card to read the next block to the play buffer. Surely, there you don't need to mix channels, processing module commands etc, but don't forget, that M65 CPU @ 50MHz is kinda fast (in fact it can emulate an intel 8080 just in software to be something like a ~12MHz 8080, what I did for some primitive software only CP/M emulator for M65). So in nutshell: I guess there is plenty of enough power in M65 to do mod playback without dedicated hw support too for sample blackback, but surely, some "cheats" (like the FIFO) can't hurt anyway :)


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