Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!kwgst From: kwgst@unix.cis.pitt.edu (Filip Gieszczykiewicz) Newsgroups: sci.electronics Subject: S100 question Summary: Doesn't ring a bell? Hit "n" now... Keywords: which is suitable? Message-ID: <83946@unix.cis.pitt.edu> Date: 27 Jan 91 07:12:02 GMT Reply-To: kwgst@unix.cis.pitt.edu (Filip Gieszczykiewicz) Followup-To: sci.electronics Organization: pre-med Lines: 93 (Please use e-mail to reply.) Greetings. This message is for people who remember S100 buss and can, perhaps, give me it's advantages and disadvantages, for a particular application, as compared with the AT ISA, Multibus and QBus. If not interested, hit "n" now. I am in the process of planning a small IBM AT add-on. It will have it's own case and be connected to the AT-buss though an interface card. The reason why I don't want to put it on one board (or a set) Is that it's components are big real-estate users. Most of the stuff will be "custom", basicly a lot of PLAs and such. Also, a lot of "discrete" LSI and SSI. It also has to be expendable in a big way. My question is really on the buss connctors and layout. I would like to use the S100 for a number of reasons: 1) It's well known and relatively reliable (and cheap) 2) Lot's of people have S100-based enclosures 3) There are a lot of pins available (lot's of possible grounds) 4) wire-wrap boards go for ~$25 each. 5) The idea of having an on-board voltage regulator is a good idea in systems that run fast and don't like noise in DC supply. Perhaps a little info on what the buss has to handle will help in your criticizms :-) I already have a 386 (33MHz) but am not impressed with the way the power of the cpu is bogged down, to a standstill, by the use of the ISA buss (AT buss) I can't really do much about it, but I _can_ do something about the way I add more features to my system. I want to have lots of digital inputs (8255s) and analog channels. I also want a way to design my own projects (such as coprocessors, controllers, etc.) I have been told, by people I consider gurus, that such things do not belong on the system buss. They belong in their own "realm" to which the system downloads problems, goes back to it's main job, and only returns to transfer the processed data back to main memory. Back to the question: I don't want people to misunderstand me. I'm not trying to use an existing buss from the compatibility point of view. All the pins in my S100 project will be my very own. What I want is a reliable and proven array of connectors, pin spacings, noise problems, proto-boards, and other matters which make the final system reliable. So, can anyone suggest a better "card cage"? I was looking at the Multibus I and II, but they are much too expensive. The card cage also is hard to come by. I have also looked at the QBus, but finding proto-card can be an adventure. And, last but least :-), there is the original AT connector and wire-wrap board. The only problem is that it's small, compared to the above board, and has many less pins. Not that I plan to use them all. I want at least 20 or so for grounds and, with the AT connector, there aren't that many left. One more thing, I want the buss to be able to handle fast clocks on parts of it. That is, there may be a set of pins that operate at a high speed, compared to the rest, without interference. I plan to use the "not used" pins, on the opposite side of the card-edge, as grounds. One thing though, why _did_ the S100 buss die? If IBM used the S100, would it be the most popular "standard" now? Or was(is) something just _wrong_ with it? Take care. P.S. Please don't just say "You're an idiot, stick with NuBus" or the like. I would like people to give me "reasonable" comments. Also, please e-mail. I will archive and make it available. -- ------------------------------------------------------------------------------ If reply bounces, try "kwgst@pittvms"... no? try "fmgst@unix.cis.pitt.edu" Did you hear? Some Poles burned the Russian flag near the Soviet embassy, in Poland. :-) :-) "Nothing is impossible if you don't have to do it yourself."