Zilog Z280

The Zilog Z280 was a 16-bit microprocessor, an enhancement of the Zilog Z80 architecture, introduced in July 1987. It was basically the Z800, renamed, with slight improvements such as being fabricated in CMOS. It was a commercial failure. Zilog added a memory management unit (MMU) to expand the addressing range to 16 MB, features for multitasking and multiprocessor and coprocessor configurations, a 256 byte cache, and a huge number of new instructions and addressing modes (giving a total of over 2000 combinations). Its internal clock signal can be configured to run at 1, 2 or 4 times the external clock's speed (e.g. a 12MHz CPU with a 3 MHz bus). More successful extensions of the Z80-architecture include Hitachi HD64180 in 1986 and Zilog eZ80 in 2001, among others. See further Zilog Z800.