What ever happened to the Z800?
(Ralph Becker-Szendy, Frank Zsitvay) The Z800 was planned to be NMOS, and was finally implemented as the Z280 in CMOS, five years late. And it does have a 4kB/8kB paged MMU, and separate I/D space, and cache. There are small differences between the Z800 preliminary spec and the final Z280 specification. The call for Z280 end-of-life last time buys went out in December, 1995. The Z180 was not an outgrowth of the Z800. It was a joint effort between Zilog and Hitachi. The first two versions of the HD64180 were slightly different from the current Z180. The current HD64180 and Z180 are identical, and both have flags in one of the control registers to emulate the earlier versions. The changes are mostly bus timing, as the HD64180 was designed to interface with Motorola 6800 style peripherals as well as Intel and Zilog, which wasn’t too strange since Hitachi second sources some Motorola 6800 series products.
The Z800 was planned to be NMOS, and was finally implemented as the Z280 in CMOS, five years late. It has a 4kB/8kB paged MMU, and separate I/D space, and cache. There are small differences between the Z800 preliminary spec and the final Z280 specification. The call for Z280 end-of-life last time buys went out in December, 1995. The Z180 was not an outgrowth of the Z800. It was a joint effort between Zilog and Hitachi. The first two versions of the HD64180 were slightly different from the current Z180. The current HD64180 and Z180 are identical, and both have flags in one of the control registers to emulate the earlier versions. The changes are mostly bus timing, as the HD64180 was designed to interface with Motorola 6800 style peripherals as well as Intel and Zilog, which wasn’t too strange since Hitachi second sources some Motorola 6800 series products.
