Take another look at Tom's VC DO
VC'd wavetable monosynth, basically.
http://www.electricdruid.net/index.php?page=projects.vcdowe can use his code, here
http://www.electricdruid.net/code/VCDO1.ASM and modify it to drop unneeded VC inputs.
Change them into a bus port and select lines.
PICs are very simple to config. They are RISC Harvard Arch.
we can port over code to a larger chip if we need more ports to config.
You can read his code to get an idea of the formula's he's used and his conversion of the wavetables to a PWM output.. evidently it's a high Hz and needs filtered to sort out the Audio.
Looks like it's not setup for a VCA.. guess we could do that separate using an example circuit from other synths if needed.. or use an off the shelf VCA chip.
Would you be using S&H methods to distribute VC's out from the DAC with a 3 to 8 decoder or some method like that?
Google "Knowles Know It All PIC microcontroller" to find a posted PDF of a very good book on PICs to evaluate. I liked it so much that I bought a book copy on ebay for cheap.. which I highly recommend for you as well.. these are great little devices.