Mixsonian


My First Home Computer - IMSAI 8080

In 1975, the magazine Popular Electronics came out with an article about how to build you own "home computer" based on the Intel 8080 microprocessor, the Altair 8080. This was the real start of the Personal Computer revolution although it was not until a couple years later when the first IBM PC came out that the term "Personal Computer" replace the term "home computer". I had subscribed to Popular Electronics for years and had built several of the projects they had in their articles (see story) but when I saw the article on the home computer, I thought it was the neatest thing and read everything I could about it. One of the student operators that worked for me at CIRCA bought one, assembled it and showed it to me and I had some reservations about buying one. The next year, in 1976, another company came out with a improved version of the Altair called the IMSAI 8080 and decided to buy one. I went all out, spending over $2000 to get a whopping 16K of memory, a ROM board, a cassette interface, parallel interface, and serial interface. The system came just a couple of weeks before I was going to move to Melbourne (see story) and so I waited to starting putting it together until after I moved, man was it hard to wait. As soon as I got settled in my new place I started putting it together. The entire system came as a kit, down to each circuit board and chips. The memory boards were the worst to assemble for at the time there were only 2Kx1 bit memory chips. At the time I thought it would be best to put all the chips on the circuit boards on sockets so that if one went bad I could replace it. In the long run this turned out not to be such a good idea because there were often problems with bad connections. Sometimes the system would stop working and I would take out a board and take a rubber mallet and "reseat" the chips. The only storage was audiocassette. To get the system going you had to toggle in a small boot program that would then read in a larger program from the cassette. I bought an ADM "glass teletype" terminal for the console. About the only thing it could do was run basic (developed by Bill Gates) and play a few games. I continued to upgrade the system over the next couple of years adding a dual 8-inch floppy disk, 48K of memory and a very early memory mapped video card. With the addition of the floppy disk it actually became a usable system running the CPM operating system and Wordstar for word processing. I had an old used Centronics line printer for printing.

I remember telling Harold Topol who I worked for about my computer and describing it to him. He couldn't see what good it was other than playing with. I told him that in a few years every small business and many homes would have one. I don't think he believed me but when the IBM PC came out in 1981 I think he started to have second thoughts. By 1984 he was doing quite a business installing and developing programs for small businesses in the area using the IBM XT.

I sold my IMSAI 8080 in 1988 in a garage sale for I was moving to Virginia for a new job.  Years later I regretted selling it for it was something special.