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RE: [N8VEM-S100:7747] Re: A new Z80 based SBC to get beginners started on the S100 bus

There are numerous ways to do this Frank, I opted for the most basic hardware approach using 74LSxxx. This allows for very simple hardware debugging. Later one can easily use and learn how the S100 bus signals are generated/formed etc. using a scope/logic probe step by step.   The challenge with boards like this is getting them working with older pre IEEE-696 S100 boards found in many S100 boxes. Few even old Z80 boards worked with all boards.

Having spent the best part of a year on a CPLD based  80386 and 80486 based S100 boards I can tell you it's not as easy as you may think.

That said if you have time I'm sure some S100 users would appreciate a CPLD Z80 board.

John

PS can you also add your name to the S100Computers GG:-
https://groups.google.com/forum/?fromgroups#!forum/s100computers

John




-----Original Message-----
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] 
Sent: Wednesday, October 14, 2015 11:57 AM
To: n8vem...@googlegroups.com
Subject: RE: [N8VEM-S100:7747] Re: A new Z80 based SBC to get beginners started on the S100 bus

Hello All,

    This is my first time with the group, so please bear with me.  I agree with "ICyoung" that the CPU board should be simple, and like the idea of a USB link to a host computer to provide low cost terminal/loader/storage.  Assume a person has an S100 bus system, the idea is to start with the CPU board.  Then a board at a time can be added, working with the CPU board to check out each board and get it working before going to the next.

    Using a CPLD for the logic would probably be easiest as they can be programmed from an old style PC printer port with an easily built cable.  There is software to make a schematic using standard TTL parts, and then compile and load it.

    Providing a simplified CPU board that can be used for system checkout and wouldn't cost a great deal would help the beginner a lot.  If simple enough it could be professionally built, providing a "plug and play" environment for us dummies.

- Frank Wilson


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