The IMSAI 8080 was an early microcomputer begun in late 1975, based on the Intel 8080 and later 8085 and the S-100 bus. It was compatible with its main competitor, the earlier MITS Altair 8800, by which it was inspired. The IMSAI is largely thought of as the first "clone" computer. The IMSAI machine used a highly modified version of the CP/M operating system called IMDOS. It was designed, made and sold by IMS Associates, Inc. (later renamed "IMSAI Manufacturing Corp"). In total, between 17,000 and 20,000 units were produced from 1975 until 1978.