That was an inspired design. I modeled it somewhat with a 4/Z80 S100 crate back in '81. I learned alot about parallelism, process sharing and multi-CPU task building and scheduling. In the end one 16mhz z80 can and will blow the doors off of 4 4/mhz Z80s generally. The complexity of supporting multiple CPUs makes it hard to get significantly improved performance without application tailoring. Allison