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Thursday, May 9, 2013

S100 Computers - Great web site for S100 and other Vintage Microcomputers

 John Monahan is the host of a web site that is full of information for S100 computer enthusiast . John's site is loaded with very useful and interesting information.  I have always been interested in the history of microcomputers and microprocessors and John has a really nice "Short History of Microprocessors".

John Monahan
You can learn  about historical microcomputers by viewing this site - Some of the things included are; Other web sites for computer collectors, Forum where you could ask your own questions, Many software programs for S100 systems, S100 Boards for sale - you can sell your own as well and much more.


Here is example of information from the web site about S100 history.
S-100 Bus Components:-The Bus & Motherboards ( This is direct from John's web site )
The reason the S-100 bus became the de facto standard for early computer hobbyists back in the 1970's and early 80's was that one was not aligned to any one manufacturer. During that time there was an explosion of information and interest in home computers. Early companies were very creative in designing boards with unique features. They all could function together if they were plugged into a S-100 motherboard. The IMSAI computer probably being the best known example of this. Early motherboards were nothing more than 100 pin connectors wired in parallel. The first home computer the Altair, had a bus structure like this. A small motherboard of 4 board slots could be joined to multiples of these boards to make a bus of up to about 16 board slots.  This arrangement worked fine for a low clock speed 8080 CPU running at 2 MHz. Soon afterwards another company IMSAI came out with a more noise resistant data bus with all connectors on one board. This quickly became the de-facto "S-100 bus computer".  While it is easy to look back now at the early Altair S-100 computer and see how it could have been improved, we should remember however, that when Ed Roberts started there was severe price constraints of what the system could cost.  It was this low cost that got the home computer concept going amongst hobbyists and launched the industry.
Altair & IMSAI Computers
However soon people wanted to increase the speed of the bus. Longer multiple board slots soon appeared. It was not long until other electronic engineers got involved and started producing "active terminated" signal lines.   The Godbout 19 slot S-100 bus board was one of the most popular. This motherboard had pull up and down resistors on each of the data, address and control lines to reduce signal noise.  A schematic of this arrangement is illustrated here. Later many commercial and homebrew S-100 systems had at least 16-18 slots in a board cage to which multiple boards from multiple manufactures were added. This became the standard home computer setup of the late 1970's. 

Take the time to look at the S100Computers web site for interesting  and useful information about S100 bus  and other vintage computers. Thank you John for listing a link to this blog on your site. I have a link to S100computers on the tab  "Web sites and Blogs" so users will always easily find John's web site from  this blog.

I just got started on my "Basic Electronics" video course - here is beginning "Electricity - What is it?"

Send a Tweet'CLICK' hashtag #KK4WW if you enjoy the blog or have a comment  Appreciate a like on Museum Facebook Page.

 I am really enjoying writing this computer informational blog. I have met many vintage computer hobbyists and learned more about historical microcomputers. One is never too old to learn - I have been a involved with computers for more than 55 years and am  always excited to find new information.  I am looking for good weather now as the "Floyd Auto Fair" is at our Chantilly Farm this weekend. It is a busy month for me as we also have our 3rd annual "Bluegrass and BBQ"   Festival  at the farm  on the 25th. Gosh I guess I am still going strong at 74 but having the time of my life.

"by David Larsen", KK4WW Computer Collector/Historian in Floyd County Virginia.