I know someone who built his first computer from a kit in 1966. At least that’s the story we’ve always been told. What kinds of kits were available back then to build your own computer? (I know nothing about what functionality this computer might have had. Zero. For all I know it was just a box with blinkenlights.)
There was the “Paperclip Computer” which evolved into the CT-650.
There was also the Heathkit EC-1. This was an analog computer, so not really a computer in the modern sense of a digital computing machine.
http://www.heathkit-museum.com/computers/hvmec-1.shtml
And then there was teh Minivac 601.
CARDboard Illustrative Aid to Computation. Best damn cardboard computer ever made (for only having 10 opcodes and 100 words of storage). From 1968.
I had a Tandy SF-5000 ca. 1972, and they may have been around earlier. Sold by Sears Scientific. Billed as an “electronic digital” computer, it was neither. More of an electro/mechanical calculator, but it was programmable and it did compute after a fashion.
Would you believe 1958? A friend had a computer “kit” he assembled. It was basically a pegboard with pegboard wheels, jumpers and insertable electrical contacts. Put together the right way, set the wheels, and it would give you a mathematical answer in lights. Really more of a demonstration calculator, but ya gotta start someplace.
It was 1976 before I got something more, and it was an IMSAI 8080.
I had this Brainiac computer kit in the early 60’s
http://goodcomics.comicbookresources.com/2006/11/30/comic-book-urban-legends-revealed-79/
My recollection is that it was and analog rather than digital computer.
That would be the GENIAC.
Various web sites with information, some with pictures:
Wikipedia page: Geniac - Wikipedia
Computer History Museum on-line catalog page: http://www.computerhistory.org/collections/catalog/X734.86
Early Computers page: EarlyComputers: The Geniac.
Some collector’s page with no info but a good picture: http://userwww.sfsu.edu/hl/c.Geniac.html
The Computer Collector: Geniac document archive: Computer Collector - Geniac Document Archive
There were also “computer” kits that were actually logic-gate demo kits, using tubes. Demonstrated simple single-bit addition, which demonstrated, sort of, the way the internals of a computer worked. I remember seeing such a kit article in an old electronics project magazine.
Somewhere in my papers I have a copy of the Radio Electronics “build your own computer” from 1973. (The head of tech where I worked left it in his papers when he quit in 1980). It was an 8008 with 256 Bytes (!) of RAM.
Before that, lots of things were called “computers” but for the average layman, odds are they were calculators or similar. An actual device where bot the program and data resided in memory would require quite a bit of memory. The RE model was cutting edge, using IIRC 16-flip-flop chips. Bulding just 1 bit of memory would be a beginner kit in the 60’s.
Can anyone identify this one? Not a kit, sold ready-to-use ca. 1968, but continued into the 70’s, it was a typewriter-sized box. It looked a lot like a large calculator, but could accept a program (yes, a real program!) that was stored on magnetic cards. The cards were a little slimmer and longer than IBM punch cards, made of plastic with a mag backing. You could record the program steps on the front, but that was just for humans – the machine couldn’t read handwriting.
It had a primitive instruction set, RAM, comparative ops, and a few (16?) registers that could be loaded either from the program or the keyboard. You could include loop instructions and IF/THEN branches. You could write the programs yourself or use the sample ones that came with it. Typical uses would be in a bank or brokerage, calculating interest payments, present value, future value, etc.
You fed the card into the machine, it read the program and stored it for execution (one program at a time). I think the output was a row of 8-segment LEDS (numeric only, plus error codes, IIRC).
I think the retail price was about $1500. I can’t remember the brand or model (Olivetti?). Surely someone remembers this machine?
I remember devices like your description in that timeframe. I never had occasion to work with them, but I recall seeing them in ads. My memory is no more specific than yours, so I can’t add any details beyond “You aren’t hallucinating.” And I give a soft upvote for Olivetti being one of the manufacturers of such.
ETA: This is NOT your device OLD-COMPUTERS.COM : The Museum but might give you some more handles to search by.
ETA2: that site has LOTS more obscure stuff in it. The UI is primitive, but it rewards a little patience.
Found it. Or at least something very like it:
IIRC, lots of other office machine manufacturers were doing similar things. E.g. SCM, Burroughs, and a couple other then-household names stuck now on the tip of my tongue.
Sorry that took so long. 
That matches in many ways if you allow for my faulty memory. However, the HP 9100, which obviously was a ripoff of the Olivetti, might have been the one I saw. The Olivetti doesn’t look like it has a display, just a printer (and I don’t remember the printer part at all). I was off on the price, too. It was either $3000 or $5000 according to the data here.
I wonder if they were program & memory card compatible.
The brokerage I worked for got this unit as a demo, and let me play with it, but they decided it was too costly. They had an IBM 360 upstairs if they REALLY needed to compute something.
The description of the Olivetti memory as a physical delay line is interesting:
My high school had a HP 9100! It came out in 1968, and HP placed one in my high school in 1968 or 1969. I was a junior or senior there then. That was my first introduction to computers.
It was placed in the room of one of my math teachers. There were two or three students (myself being one of them) who immediately got all into it. He let us hang out in his room during lunch time every day, for us to play with it. That is where I first learned about computer programming.
Maybe, maybe not. So-called Marchant calculators (Marchant Calculating Machine Company - Wikipedia) were made by all the main typewriter / business machine companies. And all saw the coming of electronics as both an opportunity and a threat.
So everybody and his brother in the mechanical business machine industry was building primitive desktop electronic calculators and they were wading haltingly into the stored-program desktop computer space. For very tiny values of “stored program” and “computer”.
Meantime the pure-play electronics companies, HP to the fore, were also invading the same space from another direction.
Then, as now with phones and apps, technologies & engineering practices were advancing so rapidly that devices were obsolete upon introduction to the market. The difference is that unlike modern $1.99 apps, these things cost serious money.
The combination of technology revolution and rapid obsolescence ripped through the forest of long-standing business machine companies like a forest fire through dry pine woods. Darn few of the big names of 1955 were still alive in 1975.
We had one of those in high school my senior year. $2000 and less computing power than a $5 pocket calculator today. I wrote a few programs for it.
Thanks, everyone.
Nothing at this level that went into production in 1965 would have used LEDs. The first (small) semi-economical ones didn’t appear until 1968. Incandescent or neon indicator lamps were used in seven-segment displays in that era. Neon was a good choice given their longevity, and power requirements weren’t an issue for a desktop device.
Forget ye not the Illuminant Glorye of ye Olde Nixie tube: Nixie tube - Wikipedia