Archive for October, 2014



The COSMAC ELF was an RCA 1802 microprocessor-based computer based on a series of construction articles in Popular Electronics magazine in 1976 and 1977. Through the back pages of electronics magazines, both Netronics and Quest Electronics offered low-priced kits that were based on this design. The system was a very early personal computer. It was operated without built-in ROMs and programs were entered directly with help of the CPU integrated DMA.

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OSI Superboard (I and II)

OSI Model 500 (Superboard I)

OSI Model 500 (Superboard I)

Ohio Scientific Inc. was a US based computer company that designed microcomputers from 1975 to 1981. The OSI Model 500 system was their earliest system, launched in 1977. It was a very simple single-board computer based on the MOS Technology 6502 microprocessor, but it lacked video circuitry, therefore a serial terminal had to be used. All of the computers that OSI’s went on to design used the 6502. In 1978, they released the Superboard II, also known as the Model 600. It was only available as a ready-built system, although the user had to build or buy a five volt external power supply to power it. The Superboard II included a keyboard, 4K of RAM, BASIC-in-ROM and cost just $279. OSI’s Challenger 1P and Challenger IIP-MF computers used the Superboard II as their main boards. Continue reading OSI Superboard (I and II)…

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Nascom 1

The Nascom 1 was the first in a series of two single-board computer kits released between 1977 and 1979 by Nasco in the UK. They were both based on the Zilog Z80 microprocessor and included a keyboard and video interface, a serial port and two 8-bit parallel ports. The system was unique for the time, since it included a full “real” keyboard and a video interface was uncommon. The hobbyist had to hand-solder about 3,000 joints on the board.
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Podcast Episode 3: IMSAI 8080 and Processor Technology Sol

Listen along as David Greelish and Jeff Salzman discuss the history of the IMSAI 8080 and Processor Technology Sol computers.

The IMSAI 8080 is a Tier One computer presented as the first Altair clone computer. As such, it was chosen to be the first computer we choose in a follow up podcast after the Altair.

The Sol was a Tier One computer chosen due to its early design as an all-in-one computer (minus monitor) and having a built-in keyboard. It is also an S-100 system.

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Processor Technology Sol

Sol-20 with it's distinctive blue color and wooden sides

Sol-20 with its distinctive blue color and wooden sides

The Altair, the IMSAI, and then later, many other microcomputers created a cottage industry. MITS and IMS Associates only offered a limited number of products and upgrades, if you could get them given the high demand for them at the time. Gary Ingram and Bob Marsh, two friends in Berkeley, California, saw this as a business opportunity. Marsh, an active member of the Homebrew Computer Club, would hear complaints about the Altair at every club meeting, so with Ingram, they decided to form a company called Processor Technology Inc. Their first product was a reliable, static 4 kB memory board for the Altair, as they knew that MITS was producing an unreliable dynamic version. Processor Technology’s 4KRA RAM board became an almost instant hit and launched the company into a thriving business. Ingram and Marsh were then able to move out of their garage workshop and into a large industrial facility.

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