Several years ago I thought I'd just use another CPU for sound alone when things are overclocked so as to get right pitched sound.... but now, being much smarter and more experienced, and having few NES and spare parts I see its not that simple at all.
There's fair share of things I don't know yet but so far my problems are :
*Its a CPU not a peripheral and likes to run on its own, and has no Halt signal like Z80 and 68K do. This would probably also mean that one cannot just overtake the CPU bus and write stuff to the chip to get funstuff happen (in current case, sound).
*There's the DPCM channel and it likes to use DMA or something similiar and can generate interrupts, this would mean the chip will have to have data available to it where the chip wants... and there's certainly games which rely on correct operation of those interrupts...
*The CPU would need a program to run, and possibly needs it to scan the activity of the other CPU and catch its sound writes, but I am quite certain the stock clock CPU will not be fast enough and combined with problems mentioned earlier I think its safe to say that this is not going to work at all.
I am probably better off with a clone CPU that runs near NTSC clock speed in PAL mode (and suffer incorrect audio as most of them tend to get some aspects wrong) or I'd have to use real NTSC CPU with right clock to get faster CPU and good sound.
This will help with slower clock of PAL CPU, but overclocking part with right sound is still not going to happen.
Right now I'm socketing my chips and I got a clone machine with socketed chips too so i'll experiment a bit aswell ^^
There's fair share of things I don't know yet but so far my problems are :
*Its a CPU not a peripheral and likes to run on its own, and has no Halt signal like Z80 and 68K do. This would probably also mean that one cannot just overtake the CPU bus and write stuff to the chip to get funstuff happen (in current case, sound).
*There's the DPCM channel and it likes to use DMA or something similiar and can generate interrupts, this would mean the chip will have to have data available to it where the chip wants... and there's certainly games which rely on correct operation of those interrupts...
*The CPU would need a program to run, and possibly needs it to scan the activity of the other CPU and catch its sound writes, but I am quite certain the stock clock CPU will not be fast enough and combined with problems mentioned earlier I think its safe to say that this is not going to work at all.
I am probably better off with a clone CPU that runs near NTSC clock speed in PAL mode (and suffer incorrect audio as most of them tend to get some aspects wrong) or I'd have to use real NTSC CPU with right clock to get faster CPU and good sound.
This will help with slower clock of PAL CPU, but overclocking part with right sound is still not going to happen.
Right now I'm socketing my chips and I got a clone machine with socketed chips too so i'll experiment a bit aswell ^^