# Processor Technology

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Personal computer company, founded 1975

Processor Technology Corporation 6200 Hollis Street in Emeryville, California, site of Processor Technology Corporation's former headquarters Industry Computer Founded April 1975; 51 years ago (1975-04) in Berkeley, California Founder Gary Ingram Bob Marsh Defunct May 1979; 47 years ago (1979-05) Fate Dissolved

**Processor Technology Corporation** was a [personal computer](/source/Personal_computer) company founded in April 1975, by Gary Ingram and Bob Marsh in [Berkeley, California](/source/Berkeley%2C_California).[1] Their first product was a 4K byte [RAM](/source/Random-access_memory) board that was compatible with the [MITS](/source/Micro_Instrumentation_and_Telemetry_Systems) [Altair 8800](/source/Altair_8800) computer but more reliable than the MITS board.[2] This was followed by a series of memory and [I/O](/source/I%2FO) boards including a video display module.[3]

*[Popular Electronics](/source/Popular_Electronics)* magazine wanted a feature article on an intelligent [computer terminal](/source/Computer_terminal) and Technical Editor Les Solomon asked Marsh and [Lee Felsenstein](/source/Lee_Felsenstein) to design one. It was featured on the July 1976, cover and became the [Sol-20](/source/Sol-20) Personal Computer.[4] The first units were shipped in December 1976 and the Sol-20 was a very successful product.[5] The company failed to develop next generation products and ceased operations in May 1979.[6]

## History

Bob Marsh, [Lee Felsenstein](/source/Lee_Felsenstein) and [Gordon French](/source/Gordon_French) started designing the [Sol-20](/source/Sol-20) between April and July 1975. The Sol-20 utilized the [Intel 8080](/source/Intel_8080) [8-bit](/source/8-bit) [microprocessor](/source/Microprocessor) chip, running at 2 MHz. A major difference between the Sol-20 and most other machines of the era was its built-in video [driver](/source/Device_driver), which allowed it to be attached to a [composite monitor](/source/Composite_monitor) for display. The Sol-20 consisted of a main [motherboard](/source/Printed_circuit_board) (PCB) mounted at the bottom of the case, and a five slot [S-100 bus](/source/S-100_bus) card cage. The main PCB consisted of the [CPU](/source/CPU), memory, video display, I/O circuits. Inside the case included power supply, fan, and keyboard. The case was painted '[IBM](/source/IBM) blue' and the sides of the case were made of solid oiled walnut originally salvaged from a [gun stock](/source/Gun_stock) manufacturer.[7]

Processor Technology manufactured approximately 10,000 Sol-20 personal computers between 1977 and 1979. All Processor Technology products were available either fully assembled, or as [electronic kits](/source/Electronic_kit). Processor Technology also sold software on [Compact Cassette](/source/Compact_Cassette_(data)). One side of the tape was recorded in CUTS format, and the other side was [Kansas City standard](/source/Kansas_City_standard) format. Gary Ingram and Steven Dompier wrote the original software utilities. Lee Felsenstein wrote the original user manuals as a contractor.

## Standards

Processor Technology also designed several S-100 bus boards. The boards were meant to be compatible with the circuits of Sol-20.

The **Video Display Module 1** ([VDM-1](/source/VDM-1)) was the original video display interface for S-100 bus systems.[8] The board generates sixteen 64-character lines of upper and lower case typeface on any standard [composite video](/source/Composite_video) monitor or a modified TV set. Utilizing a 1,024 byte (1K) segment of system memory, the VDM-1 provided [memory-mapped I/O](/source/Memory-mapped_I%2FO) for high performance, and also included hardware support for scrolling. The VDM-1 Video Board was a great improvement over using a [teletype machine](/source/Teleprinter) or a serial attached terminal, and was popular for owners of other S-100 bus systems such as the [IMSAI 8080](/source/IMSAI_8080).

Another popular product was the **CUTS** Tape I/O Interface S-100 board. The CUTS board offered standard interface for saving and reading data from [cassette tape](/source/Cassette_tape), supporting both the [Kansas City standard](/source/Kansas_City_standard) format, as well as their own custom CUTS format. Lee Felsenstein was key participant of the development of Kansas City standard format, the first cross-system data transfer standard for [microcomputers](/source/Microcomputer).

## Products

Processor Technology Sol-20 Computer designed by Bob Marsh, Lee Felsenstein and Gordon French

- Computers - Sol-PC — Single circuit board only without case or power supply; available as fully assembled or as kit form - Sol-10 Terminal Computer — Stripped-down model without 5 slot S-100 [backplane](/source/Backplane); available as fully assembled or as kit form - [Sol-20 Terminal Computer](/source/Sol-20) — Includes 5-slot S-100 backplane; available as fully assembled or as kit form - Sol-20 price 1976 approximately $5000 CND with extra 16K card

- S-100 bus boards - [VDM-1](/source/VDM-1) — Video Display Module Board - [3P+S](/source/3P%2BS) — Input/Output Module 3 [Parallel](/source/Parallel_port) plus 1 [Serial](/source/Serial_port) Board - 4KRA — 4K [Static Memory](/source/Static_random-access_memory) Board - 8KRA — 8K Static Memory Board - 16KRA — 16K [DRAM](/source/DRAM) memory board - 32KRA-1 — 32K DRAM memory board - CUTS — Tape I/O Interface Board, CUTS format and [Kansas City standard](/source/Kansas_City_standard) format - 2KRO — [EPROM](/source/EPROM) memory board - Helios II Disk Memory System - GPM — General Purpose Memory, [ROM](/source/Read-only_memory) board held CUTER Monitor Program

- Software - SOLOS — [operating system](/source/Operating_system) - CUTER — [monitor](/source/Machine_code_monitor) program and cassette tape loader. - ASSM — 8080 [assembler](/source/Assembly_language#Assembler) - BASIC/5 — 5K [BASIC](/source/BASIC) [programming language](/source/Programming_language) - Extended Cassette Basic (8K) — BASIC Interpreter - [FOCAL](/source/FOCAL_(programming_language)) programming language - ALS-8 - [PTDOS](/source/PTDOS) — operating system for use with the Helios II Disk Drive - EDIT — 8080 Editor - 8080 Chess — Chess Game - *[TREK-80](/source/Trek-80)* — *[Star Trek](/source/Star_Trek)* Themed Game - GamePack 1 — Collection of Games - Volume 1 - GamePack 2 — Collection of Games - Volume 2

## Works cited

- [Freiberger, Paul](/source/Paul_Freiberger); [Swaine, Michael](/source/Michael_Swaine_(technical_author)) (2000). [*Fire in the Valley: The Making of the Personal Computer*](https://archive.org/details/fireinvalleymaki00frei_0) (2nd ed.). New York, NY: McGraw-Hill. [ISBN](/source/ISBN_(identifier)) [0-07-135892-7](https://en.wikipedia.org/wiki/Special:BookSources/0-07-135892-7).

- Veit, Stan (1993). *Stan Veit's History of the Personal Computer*. Alexander, North Carolina: WorldComm Press. [ISBN](/source/ISBN_(identifier)) [1-56664-030-X](https://en.wikipedia.org/wiki/Special:BookSources/1-56664-030-X).

## References

1. **[^](#cite_ref-1)** Freiberger (2000), 61-63

1. **[^](#cite_ref-4KRA_RAM_2-0)** [|Marsh, Robert (July 1975). "4KRA (4096 x 8 RAM) Static Memory Module". *Homebrew Computer Club Newsletter*. **1** (5). Menlo Park, CA: 2.](http://www.bitsavers.org/pdf/homebrewCC/HCC_Newsletter_V1_N05.pdf)

1. **[^](#cite_ref-PT_Ad_Oct_1976_3-0)** "Make a Giant of Your Minicomputer". *Byte*. **1** (14). Peterborough NH: Byte Publications: 72–73. October 1976. A Processor Technology advertisement showing a motherboard with eight add-in boards.

1. **[^](#cite_ref-Marsh_1976_4-0)** Marsh, Robert; Lee Felsenstein (July 1979). "Build the SOL Intelligent Computer Terminal". *Popular Electronics*. **10** (1). Ziff Davis: 35–38.

1. **[^](#cite_ref-5)** Veit (1993), 131-148

1. **[^](#cite_ref-6)** Freiberger (2000), 153-155

1. **[^](#cite_ref-SS1_7-0)** Lundin, Leigh (2011-10-09). ["An Apple Today"](http://www.sleuthsayers.org/2011/10/apple-today.html). *Technology*. [Orlando](/source/Orlando%2C_Florida): SleuthSayers.org.

1. **[^](#cite_ref-Byte_Nov_1975_8-0)** Processor Technology (November 1975). "8800 Hardware". *Byte*. **1** (3). Peterborough, NH: Green Publishing: 75. Processor Technology advertisement. The VDM-1 Video Display Module for the Altair computer generated 16 lines of 64 characters on a black and white TV. Kit price was $160, assembled $225. The Cromemco TV Dazzler first appeared in the April 1976 issue of Byte

## External links

- [Archive of Sol-20 information](http://www.sol20.org/)

- [Collection of old analog and digital computers at www.oldcomputermuseum.com](http://www.oldcomputermuseum.com/)

- [the SOL-20 at old-computers.com](http://old-computers.com/MUSEUM/computer.asp?c=344)

- [Processor Technology SOL - PC History by Stan Veit](http://www.pc-history.org/sol.htm)

- [Processor Technology SOL-PC – An early Sol-20 minus the 20](https://vintagecomputer.ca/processor-technology-sol-pc-an-early-sol-20-minus-the-20/)

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Adapted from the Wikipedia article [Processor Technology](https://en.wikipedia.org/wiki/Processor_Technology) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Processor_Technology?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.