View Full Version : homebrew s-100 system

August 4th, 2003, 03:14 PM
what is an easy way to make a homebrew s-100 motherboard?

I want to build the computer using mostly breadboard and homemeade PCBs where necessary... is there an easy way to make a motherboard to connect the different (home designed and built) boards without buying 100-pin connectors?

PS my system is called the Llama-80 and uses an 8080a, for those interested

August 4th, 2003, 03:41 PM
You could do all sorts of things up to and including hard-wiring the entire bus and soldering boards onto that.

In the end, though, is it really S-100 if you don't use the actual S-100 connectors?

You can breadboard or homebrew everything else. . .


August 4th, 2003, 03:43 PM
true... its not really an S-100 system in the true sense of the word, it just uses the bus... i planned on hardwiring everything together and just using the S-100 bus as a guideline because im using the Altair schematics for my memory board(s), and they need to be compatible (obviously)

is there any easy way to adapt the altair schematics for use with a Z80? i hadn't thought about it till now, when i was looking at prices.

August 4th, 2003, 03:47 PM
In that case you can do a "bus free" design and just wire appropriate pins together from board to board, eliminating the backplane.

Basically it would be similar to what Jon Titus did with the original Mark-8 kit where he just had a sandwitch of boards with wires bridging between them.


August 4th, 2003, 05:20 PM
Basically it would be similar to what Jon Titus did with the original Mark-8 kit where he just had a sandwitch of boards with wires bridging between them.

Any pictures of that online? Thanks for the input.

August 4th, 2003, 06:19 PM
Funny you should ask.

I just got a copy of what I think are the original Mark-8 notes as purchased through the old issue of Radio-Electronics.

I've got a scan of the front page here:


I'm going to do some research to see if this is a simple reprint or the actual build-manual purchased with the boards.

Either way, there's a picture on the front that's a B&W version of the RE cover article. The multi-colored ribbon cable is visible under the paper tape.


October 27th, 2003, 03:38 PM
My college roomate built a Mark-8. AFAIR he ended up running bare wires between the boards as the main bus. Maybe the ribbon cables for for aux data paths. Or that's a later rev.

I built a homebrew S-100 backplane using wirewrap edge connectors, and used wirewrap wire for the connections. About 4 slots. Some trim wood was used as a frame. I still have it. I also have a unpopulated S-100 backplane pc card and a Vector S-100 prototype card.

Is anyone actually building/repairing S-100 systems out there?
Where do they hang out?


October 27th, 2003, 11:29 PM
Great picture...
It sure reminds us ol' good times :wink:

June 16th, 2005, 06:54 AM
This is my homebrew s-100 system. :)


When I bought this unit some time ago, it was a wreck.
So I almost completely rewired it, and redesigned the powersupply.
The s-100 extension board is from godbout and has an active terminator circuit on it.
The front board is a KIM-1(rev.F) computer from commodore.
The two boards on the godbout board I designed myself.
One is a Ram/Rom expansion, the other is a keyboard interface.
The next board i was planning to design is a video interface, but i haven't found the time to build it yet.