On 2/24/2013 2:47 PM, Steven Hirsch wrote:
I think "Z80B" is pertinent to the first generation (1980s) parts only. That Z84 part number is the one I have in my board.
The original Z80 was rated 2.5 MHz. Z80A - 4 MHz and Z80B - 6 MHz.Then it was second, third, etc. sourced by quite a few companies rated for different speeds. The most advanced parts are Z84C00xx, where "C" means that they are CMOS and xx indicates the speed.
Using a 20 MHz CPU with a real PCPI board won't do much good as the DRAM only works fast enough for a 6 MHz clock. My version uses pretty fast (55 ns) static RAM that is happy to run at 20 MHz clock all day.
I didn't see 20 raised hands but ordered a few more PCBs. The interested parties will get a kit with a PCB and all the parts including programmed CPLD and PROM.
-Alex.