<One of the problems with the S100 bus is that it is _very_ dependant on <the 8080 signals. Even using a Z80 is a bit of work - things like PINTE <(which indicates if interrupts are enabled) and SSTACK (address lines Neithrr of which had much application. <Actually, I prefer the Motorola / PDP11 idea of having memory and I/O in <the same address space. It means you can use the same instructions and <addressing modes to access either. nothing about z80, 8085 or 8088 stops one from doing that. The Northstar* floppy controller was memory mapped for exactly that reason. Allison