Original asked by : Evan Koblentz cctalk at snarc.net
On Thu Jul 19 14:36:27 CDT 2018..Zilog 8000 system (model 20 and model 32)
replacement boards
..As far as the System 8000 model 20 are conserved their microprocessor board
schematics and firmware can be found on the internet but the microprocessor and
the MMU's might be hard to get. ? (out of production for some time now).
.. As far as the MMU's are concerned some System 8000 clones used a different
MMU with a custom mapping PROM and or others use a Intelligent MCU to emulate
the Zilog MMU'sAs far as the Model 32 is concerned that a little different,
without the original microprocessor board you could always down grade it to a
lesser model. It would be easy to get the Z8001 microprocessor on to a 32 bit
data bus. Just some extra data latches if you could find some one to make a
custom microprocessor PCB.Use the Z8001 microprocessor pins Bit//word, AD0, AD1
for data bus size signals.AD1 is for data bits 17 to 24 and data bits 17 to 32
depending on the status of Bit//Word and AD0 singals.AD0 is for data bits 0 to
16 with the correct status of Bit//word and AD0 signal. Bit//Word with AD0
controllers either a upper byte/Lower byte or 16-bit word transfers...Memory
greater that 16M with the Z8001 microprocessor on a full 32-bit address bus is
possible with a paged memory management circuit. Drivers ?? by who ??..With the
model 32 (and some if its clones) on board firmware and or operating
enhancements where used for Z8001 ( and some Z80,000) microprocessor
compatibility. The only other solution is to reverse design a AT 3B2
computer back to the Zilog System 8000 bus or use a custom made ARM based
microprocessor card with Z8001 emulation in ROM. ..Most of the Z8000 based
microprocessor system I have dealt with are newer than the model 32 or are
older then the Zilog MMU's chips. ..Any feed back on this email is welcome at
ZilogZ80.swingatYahoo.ca At=@ please have a subject (Anti spam)..
