The Intel 8088 ("eighty-eighty-eight", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on July 1, 1979, the 8088 had an 8-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range were unchanged, however. In fact, according to the Intel documentation, the 8086 and 8088 have the same execution unit (EU)—only the bus interface unit (BIU) is different. The original IBM PC was based on the 8088.