MITS8800 CPU Board

[Randy McLaughlin]

From: "river" <river at zip.com.au>
Sent: Tuesday, June 14, 2005 1:23 AM


> 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 
> debug/monitors for my old Multibus stuff so I can always use one of 
> these - or mod it accordingly.
>
> 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.
>
> I'll check the MWRITE signals and see what I can do, or if you have the 
> info then that's even better.
>
> 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.
>
> Again, thanks for your help. This is my first foray into S100 stuff, and 
> makes a nice change from Multibus.
>
> rgds
> river

A few manufacturers used S100 bus with regulated power supplies including 
some CompuPro systems.  It doesn't hurt anything to plug in a card with 
onboard regulators it just won't work without bypassing the regulators.

Mwrite is pwr nor pout, memory cards can use pwr I/O cards can use pout but 
a 7402 can generate mwrite.

The NorthStar CPU can do most of what you want.  If you piggy back RAM and 
EEPROM and add a little logic then all you need is I/O.  The NorthStar CPU 
generates mwrite.


Randy
www.s100-manuals.com