IMSAI 8080

Back and forth in time…

IMSAI 8080 replica built by the author.

The IMSAI 8080 was the first “clone” microcomputer, introduced in 1975 – a lower cost version of the MITS Altair 8800, introduced a year earlier in 1974. I first saw the Altair on the cover of Popular Electronics. Dad got me a subscription to PE because of my insane interest in taking apart phones and other electronics that he brought home. I was very good at taking things apart, not always putting them back together again, but that didn’t matter.

I was fascinated by pocket calculators, especially the Bowmar Brain and early Hewlett Packard and Texas Instruments models. I can probably attribute almost all of this to magazines like Popular Electronics and hanging out at Wholesale Electronics in Portsmouth. I bought my first Sony Walkman there in 1980, using newspaper route savings. Dad was friends with the manager then owner, Pete Saltzman, and Pete used to give me old broken parts, and copies of Consumer Electronics magazine – a trade rag for people who sold, um, consumer electronics.

My first calculator was a hand-me-down from Dad, a four-function thing from National Semiconductor called a “Mathbox“. It was RPN, which I found exotic but loved once I figured out what it did. I bought my first scientific calculator, another National Semiconductor, from Harts Department Store, some time in middle school.

Then I learned about programmable calculators and my brain melted.

My friend, Jim Troutman, had an older brother in engineering school at Ohio State. He gave him a hand-me-down HP-35 non-programmable model, but it led me to learn about the whole HP line, where I discovered that craziness of programming. I became hooked and, my senior year of high school, bought an HP-41that I used all through college (I still have it!). I learned how to program with it, and also the craziness of “synthetic programming” from some fellow geeks at the OSU Interactive Graphics Laboratory.

I really wanted a programmable computer though. Back then, the IMSAI and Altair were just way too expensive, easily $5-10,000 in today money. Even the TRS-80 was out of our family’s budget. My high school got a single TRS-80 my senior year and they let me play with it a little. I got in trouble for naming a file FUCK.BAS but luckily Mr. Smith had a good sense of humor. Still, no IMSAI for me.

My folks bought me a TRS-80 Pocket Computer as a graduation gift and I started to learn BASIC. It was relatively affordable and super cool to have a whole ‘actual’ computer in your pocket. I programmed a baccarat game and polished up on my James Bond skills for a while. Later, while I was in college, Jim’s brother bought an Apple II and it came with a free Timex-Sinclair which I convinced him to give me, since, well, he had an Apple II.

I did my first computer graphics on that. I drew a sine wave and was so proud I took a photo.

My first computer graphics, a sine wave made with my Timex Sinclair 1000. Ruby the cat is impressed.

Soon after, I bought a Macintosh, within the first ‘100 days’ of its release that Jobs said would make-or-break it. I used it to invite my now wife back to my place to ‘show her my etchings’ and the rest is history I suppose.

That brings us back to the IMSAI. I saw a replica model that runs a beautiful z80 / 8080 emulator from an Australian company The High Nibble. It uses an ESP32-PICO-KIT running the z80pack emulation suite. It took a few days of procrastinating soldering, and I got it running. It sits peacefully on a table in my living room and has a beautifully cool web interface that lets me run things like Zork, Rogue, WordStar, the works. It is so fun to write bits in manually (but yes, tedious… bleh, who cares) and toggle the run/stop switch to see blinkenlights. I brought it in for my students to see. They have spent the semester using the Raspberry Pi Pico to make vehicles and were a little concerned that this thing uses a Pico to go back in time many decades. But, now I have a beautiful box that I lusted after as a kid, just in time to play Global Thermonuclear War.