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Show Notes: IMSAI 8080 S100 bus computer

Introduction

IMSAI 8080 S100 bus computer



***NOTE*** The IMSAI systems have now been sold and are NOT available

These two systems are the heaviest items brought down from the Attic so far. Easily weighing in at forty to fifty pounds they are pretty solidly built, an excellent representative of theearly S100 based systems and an icon in their own right as the face of personal computing as depicted in the classic movie “Wargames”. However, the Imsai was also often shown in the media at that time whenever a story needed a personal computer. With the blinking lights and rocker switch front panel, it looked both impressive and met the expectations of what people expected a computer to look like holding its own, at least in the visual media, when much more powerful, yet visually boring looking, computers started to replace the S100 systems. Within just a year or two of the introduction, more user-friendly computers appeared on the market, and IMS Associates, Inc. filed for bankruptcy in 1979.

The two units shown here are essentially a large metal case with a power supply, and numerous slots to insert the expansion cards. I bought them online back in the early nineties from what turned out to be a compute store that was going out of business. For my purchase of the two units and an ADM 3A terminal the store also sent me a boatload of S100 cards and a couple of drives for what turned out to be an excellent deal. They really were going out of business so sending it to me was a better outcome than throwing them out.

These units have installed a memory card and a serial card, to support the TTY terminal connection as nobody even back in the day really programmed the computer through the front panel toggle switches at least not past the first time entering and running the “demo” program.

I have not tried to power up these machines, and I have no idea if they are currently working, although both machines were retired to the attic, in working condition, 15 or so years ago. If you intend to use them, I strongly suggest that you hook it up to a Variac or some simiar mechanism to apply current very slowly over at least a 24 hour period. As repeating again, these computers have not been powered up for over 15 years.

In case you are comparing these with some other systems declared in working condition then note that the lights will light up on these computers with no boards installed. Don’t be fooled into thinking that because the lights are on, that the computer works, the only thing that lights appearing show is that the power supply is working (which is not a bad thing by itself - look at the size of the transformer!).

The Inside of the systems are a little dusty, but none of the component pieces or slotted cards look damaged. I have posted pictures, please look because what you see is what you will get. I am selling these computers as a display piece only, with no guarantee that it will function. Sold AS-IS,NO RETURNS.

The reality is that these computers have less computing power than your average TV Remote Control Device, so practical computing value is “nil”, but they are a fast dissappearing piece of computer history.

Status: Available [Make an Offer]

Estimated Value:
BTC Symbol 0.162 bitcoin
Note the price is for either one (NOT BOTH) of the Imsai units pictured here.


From Attic to workbench

Dinosaur Attic is a non-smoking environment, so there is no “Joe Camel” effect on electronics (or anything else) where they smell like an ashtray, but after a quick clean-up with a mostly damp cloth and some alcohol cleaner they are ready for display.

Pricing The original price for the IMSAI ranged from $2,849 to about $4200 for the kit as configured (essentially barebones).

Serial Numbers

Back of components showing the serial numbers - Open image in new window/tab for larger view.
Left to right: .
IMSAI_back IMSAI Back

The Imsai was sold as both a kit or already-assembled and tested. The kit version was hundreds of dollars cheaper, but you were looking at days or weeks of very careful soldering and assembly to create a debugged, working IMSAI. In its simplest configuration with only a CPU (Central Processing Unit) card, you enter your program using the front panel switches, while reading the results on the LED indicator lights. No keyboard or other display is necessary. This type of programming is slow, quite error-prone, and painstaking where any mistake could corrupt the system forcing you to start over again. These were NOT systems for John “Q” Public to use and needless to say at this point in time there was no such thing as a personal-computing software distribution market so very little software was available.

###References

Available S100 Cards

California Computer Systems model 2065 64K dynamic ram card

California Computer Systems model 2065 64K dynamic ram card - Revision C

California Computer Systems model 2065 64K dynamic ram card

California Computer Systems model 2065 64K dynamic ram card

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***NOTE*** The IMSAI systems have now been sold and are NOT available

Thanks DinosaurAttic.com