These S-100 microcomputers ran the gamut from hobbyist toy to small business workstation and were common in early home computers until the advent of the IBM PC.

The S-100 bus is a passive backplane of 100-pin printed circuit board edge connectors wired in parallel.

The Sol-20 used a variation that had only a single 8-bit bus and used the now-unused pins as signal grounds to reduce electronic noise.

Later, these two 8-bit buses would be combined to support a 16-bit data width for more advanced processors, using the Sol's system to signal the direction.

A bus control signal can put these lines in a tri-state condition to allow direct memory access.

Unassigned lines of the original bus specification were later assigned to support more advanced processors.

During the design of the Altair, the hardware required to make a usable machine was not available in time for the January 1975 launch date.

The "S-100" name, short for "Standard 100", was coined by Harry Garland and Roger Melen, co-founders of Cromemco.

[3][4] While on a flight to attend the Atlantic City PC '76 microcomputer conference in August 1976, they shared the cabin with Bob Marsh and Lee Felsenstein of Processor Technology.

[6] The first symposium on the S-100 bus, moderated by Jim Warren, was held November 20, 1976 at Diablo Valley College with a panel consisting of Harry Garland, George Morrow, and Lee Felsenstein.

[9] Other innovators were companies such as Alpha Microsystems, IMS Associates, Inc., Godbout Electronics (later CompuPro), and Ithaca InterSystems.

[10] In 1986, Cromemco introduced the XXU card, designed by Ed Lupin, utilizing a 32-bit Motorola 68020 processor.

[12] In July 1979 Kells Elmquist, Howard Fullmer, David Gustavson, and George Morrow published a "Standard Specification for S-100 Bus Interface Devices.

[15] As the IBM PC products captured the low-end of the market, S-100 machines moved up-scale to more powerful OEM and multiuser systems.