Zilog, Inc., previously known as ZiLOG, is an American manufacturer of 8-bit and 16-bit microcontrollers. Its most famous product is the Z80 series, 8-bit microprocessors that were compatible with the Intel 8080 but less expensive to use. The Z80 was widely used during the 1980s in many popular home computers such as the TRS-80 and the ZX81. Both 16- and 32-bit processors were also produced by the company, but these did not see widespread use. From the 1990s the company focused primarily on the microcontroller market. The name is an acronym for "Z (the last word in) integrated logic". Zilog was started in California in 1974 by Federico Faggin and Ralph Ungermann, who both left Intel after working on the 4004 and 8080 microprocessors and custom chips. Masatoshi Shima, who also worked with Faggin on the 4004 and 8080, joined Zilog in 1975. Ungermann had a falling out with Faggin and left Zilog in 1978. The company became a subsidiary of Exxon in 1980, but the management and employees bought it back in 1989, led by Dr. Edgar Sack.