The qq22. net Computer Rooms

updated 23_Oct_2007
Some of the processors I've worked with over the past thirty years...

The Z80


Z80Z80
Above are a few Z80 processors...
Zilog Z8400A - Zilog Z8400B
Mostek MK3880N - Zilog Z0840006PSC
Sharp LH0080 cpu - Zilog Z84C0010PEC

The Z80 appeared in 1976. It is an eight data bit, 16 address bit design.
Designed by ex-Intel employees, who went on to form ZILOG (Z (the last thing) I (in) LOG (logic))
An improvement over the 8080, and incorporated the 8080's instruction set. But has loads more
instructions too, Some un-documented!. More registers AF BC DE HL IX IY (in two banks).
Shown here are various devices. Speeds ran from 2.5MHz up to 8 and 10 MHz with later c-mos chips.

The Z80 was a really nice CPU to work with. It was a pleasure to Use, and has on-board RAS and CAS lines
for refreshing dynamic memory. and being code-compatible with the 8080 it was a far easier option to
use for a cp/m system. I was working for an engineering company making custom Z80 based cp/m computers
in the early 1980's some of the cards made by this company appear elsewhare on this website. They included
A/D & D/A, parallel, Serial, Hard-disc and Floppy Interfaces, Memory Expansion, and Single-board-computers.
In the late 1980's I spent a year or so hacking cell-phones based on the Z80 and the 8048/8051
The first "real" computer I used was a Z80 based Research Machines (RML380Z) with a tape drive!
later we had a 380Z with a pair of 72kb 5-1/4" floppy disc drives! before the 380Z I was writing fortran using
mark-sense cards and sending them away to be run at the local university.
I carried on working on Z80 based
systems on and off until about 1995, usually alongside 68000 based machines. I still occasionally have mad-
moments, mainly when I'm tired, When I revert to thinking in Z80 op-codes and assembley language. Usually
when I should really be thinking in PIC. more coffee, and more sleep required...

z80 processor
z80 family......


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