Zilog Z800

The Zilog Z800 was a 16-bit microprocessor designed by Zilog to be released in 1985. It was instruction compatible with their existing Z80, and differed primarily in having on chip cache and MMU for a 16 MB address range, and also a huge number of new more orthogonal instructions and addressing modes. However Zilog essentially ignored the Z800 in favour of their 32-bit Z80000 and it appears the Z800 never entered mass production. The Z280 in 1987 was another try with almost the same design, but this time implemented in CMOS.