Zilog Z280

from The Free On-line Dictionary of Computing (8 July 2008)

Zilog Z280

   An enhanced version of the {Zilog Z80} with a 16 bit
   architecture, introduced in July, 1987.  It added an {MMU} to
   expand addressing to 16Mb, features for {multitasking}, a 256
   byte {cache}, and a huge number of new {op codes} (giving a
   total of over 2000!).  Its internal clock runs at 2 or 4 times
   the external clock (e.g. a 16MHz CPU with a 4MHz bus).

   (1994-10-31)