MITS8800 CPU Board - test-drb@ccmp.vtda.org

14 Jun 2005

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Subject: MITS8800 CPU Board
   From: "river" <river at zip.com.au>
   Date: Tue, 14 Jun 2005 16:23:21 +1000
     To: <cctalk at classiccmp.org>

Hi,

Great, thanks for the info.

I'm sourcing a few S100 protoboards, so I'll be able to wirewrap a board with all
the relevant RAM, ROM and I/O. I'll probably use later generation chips such as 62256
for RAM and 6264 for ROM. I can then put in the 8251 and 8255 for serial and parallel
ports, respectively. Is that heresy in regards to these old boards?

It's not an issue to me starting ROM at 0000h. I've written a few 8080 

I've only got a 6-slot motherboard and a Northstar ZCB processor board,  S100
ROM board and some Dynabyte RAM boards and I was going to use the 
motherboard and original S100 boards with this system.  

This means the 8800CPU board will be in a small 2-slot system - the CPU board and the
RAM/ROM/IO board I'm going to make.

The NS* ZCB has a power on jump (POJ) and reset logic so you dont need 
rom at Zero plus it also generates Mwrite.  Besides being Z80 it's a 
better CPU to use.

...
 Just one more thing.... I suppose it's possible to
use the 8800CPU bd 
without the power regulation components if I ensure the correct  voltages go through
the correct pins on the bus. I can then use an 
old spare PC power supply, instead of creating a new supply. Naturally, 
this would entail that no other S100 board can be used due to their 
on-board regulators. This isn't an issue if I build my own S100 boards, 
without regulation, for this system.

You can add regulation a trivial thing.  However using a PC supply is 
fine (you'll need -5 -12 +5 +12).  Regular S100 cards can be used if 
you bypass the regulators.

...

Again, thanks for your help. This is my first foray into S100 stuff,  and makes a
nice change from Multibus.

Nice change?!?  You will be messing with hardware much more.  S100 
you'll find there are a few quirks like noisy backplanes and cards
that are S100 but not always compatable with the CPU in use.

Allison