What is the S-100 bus?
The S-100 bus, also known as the IEEE-696 bus, is a bus standard of 100 pin cards, 50 pins per side, which plug into 100-pin edge connectors on a passive (i.e. no computer logic) backplane once called a “motherboard”. Dozens of computer companies produced cards and systems to this standard in the 1970’s and 1980’s. One of the first popular microcomputers was the Altair 8800 by MITS, which was offered as a kit in the January 1974 issue of Popular Electronics. Each functional block of the computer, which at that time required many logic or memory chips each, was designed to fit a single card which plugged into a bus or “motherboard”. The function and timing of signals on the 100-pin connectors of that bus became known as the “S-100 bus”. An industry was started in producing cards compatible to the Altair, followed by the production of whole systems. The bus evolved as other manufacturers, such as Cromemco and Compupro, used slight variations of the bus design for their product line. Thes
