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)”
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. Continue reading “Nascom 1”
Listen along as David Greelish and Jeff Salzman discuss several of the early single board computers, including the Nascom 1, OSI Superboard, MOS Technology KIM-1, and the COSMAC ELF.
All of the above single board computers don’t easily fit into the History of Personal Computing’s “Tier” philosophy, so this special podcast episode was produced.
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.
The IMSAI 8080 was arguably the first personal computer clone!
Closeup view of the IMSAI 8080
With the large and growing success of the MITS Altair 8800 early in 1975, IMS Associates, Inc. of San Leandro, California was able to capitalize on its success with an improved copy. Like the Altair computer, the IMSAI utilized the S-100 bus, Intel 8080 microprocessor and a front panel with LEDs and switches. You could utilize the switches to read and write to memory locations, single step the CPU, or even stop it. The LEDs would blink according to the values inside the address and data buses. The IMSAI 8080 could run all of the same programming instructions, and later software, when it became available. IMS Associates improved just about every aspect of the Altair’s design, with a higher specification power supply, an anodized aluminum chassis, more S-100 expansion slots and a better front panel with superior paddle switches.
