The Early Microcomputer Design

A collection of early microcomputers, including a Processor Technology SOL-20 (top shelf, right), an MITS Altair 8800 (second shelf, left), a TV Typewriter (third shelf, center), and an Apple I in the case at far right.

The MITS Altair 8800 is a microcomputer design from 1975 based on the Intel 8080 CPU. The Altair bus consists of the pins of the Intel 8080 run out onto the backplane. Another oddity was that the system included two unidirectional 8-bit data bus, but only a single bidirectional 16-bit address bus.

source: wikipedia.com