I recommend a 32-bit MCU like the Atmel AVR32 instead of 8 bit. The 32-bit ones aren't conceptually any more complicated. In fact, 8-bits adds a lot of complexity in doing arithmetic and updating registers with multiple single-byte writes.
Typical AVR32s give you 32 bits, 33 MHz RISC for $12. That would have been a decent workstation in 1990.