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Processor Technology Corp
SOL - 10 / 20

The Sol Computer was developed by Bob Marsh, Lee Felsenstein and Gordon French. Bob founded his company, Processor Technology, in April 1975 making 4K RAM memory boards for the Altair (cause MITS couldn't make a working memory board)

In June 1975, Bob and Les Solomon (technical editor of Popular Electronics) dreamed up the Sol-20 computer, Bob had a bunch of cheap walnut that he originally intented to use in a digital clock, he didn't want it to go to waste and used it in the Sol-20 (see picture).

About 10,000 of them were produced, some as kits, some as pre-builts. Based on the Intel 8080 microprocessor, this machine occupies a special niche in computer history for technical and esthetic reasons. It was one of the earliest to include a keyboard interface and support circuitry for full implementation of every 8080 function. It was a pioneer towards modern video output boards by having a design that actually put up alphanumeric characters on the screen, using a form of distributed processing that didn't lean on the CPU for all processing.

There were several models of the SOL-20 system :

- The SOL System I ($1649 in kit or $2129 assembled), with SOL Operating System, 8 KB RAM, a 12" TV/Monitor, and a cassette recorder with BASIC software tape.

- The SOL System II ($1883 in kit or $2283 assembled), is a SOL System I with 16 KB.

- The SOL System III ($4750 in kit or $5450 assembled), is a system II with 32 KB RAM, a video monitor, the HELIOS II Disk Memory System and a DISK BASIC floppy.

Please consider donating your old computer / videogame system to or one of our partners from anywhere in the world (Europe, America, Asia, etc.).


Built the Sol 20 kit back in the late ''70s and bought a used one in the ''80s. They are both long gone, but I would love to add one back into my S-100 collection.

Sunday 19th September 2021
Jason (Canada)

In 1976, my husband began visiting the only computer store in the Washington area, in Georgetown after work. It took him a year to prepare me for the fact that he was going to spend a lot of money buying a computer. I thought he was having a mid-life crisis. He bought the Sol III and a printer the next year. I remember that the printer cost more than the computer. When I expressed my doubts about buying a computer, he said, "Someday everyone will have a computer in their home." He used the Sol to do genealogy and he invented a football game using text only that neighbors became addicted to. Neighborhood kids lined up to play it. When I asked if I could learn to use it, I was told that the only available time was from 3 to 4 a.m. He bought a second Sol to use for replacement of parts. One of them is in a computer museum somewhere in California, I think.

Thursday 20th April 2017
Lillian (United States)

I bought a used SOL 20 at at the Sunnyvale Swap Computer swap meet about 1979 or so. I used it to learn 8080 assembler. I still have it in the back room and have somehow protected it from the wife''s semi-annual "purge" of all that "junk". At the same swap meet in 79 I had the chance to purchase the original Intel 4040 prototype board from an old Intel engineer who was cleaning out his garage, for $5, cash. But since I had blown my wallet on the SOL, I didn''t have any money left! LOL Next year, the same engineer had realized what he had, and mounted and ''framed'' the 4040 board. It was NOT for sale...

Monday 30th March 2015
Richard Freeberg (Napa CA)


NAME  SOL - 10 / 20
MANUFACTURER  Processor Technology Corp
TYPE  Professional Computer
YEAR  End of 1976
KEYBOARD  QWERTY full-stroke keyboard
CPU  Intel 8080A
RAM  8k, 16k or 32k (up to 48 KB)
TEXT MODES  64 x 16
COLORS  Unknown
SOUND  Unknown
I/O PORTS  RS 232, cassette, S100 Bus
PRICE  Unknown

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