Owner: M. Bergman
Location: Richmond, California
It's amazing how well some of these old computers have
weathered the ages. Mathew Bergman
gives us the scoop on his old Zenith machine.
While this machine may not have the charm of an
Apple II, the fond remembrances of a C64 or the
utility of an IBM PC, it definitely has one
outstanding feature: It was built to last. By
remarkable circumstance I was given this computer
while just finishing elementary school, and pounded
it playing ASCII-based games, word processing and
BASIC programming through my Sophomore year in
college in 1991. As evidenced by the picture, it's
barely the worse for wear. Throughout its active life
it was connected to a Transtar daisy-wheel printer
(still clacking away, though no drivers are available
for it) and an acoustic-coupler 300 baud modem (since
lost, although it never really worked anyway).
Although this machine is still fully functional, it
is now mostly used as a conversation piece.
Zenith Data Systems was founded in 1979 by Zenith
Electronics Corporation, after acquiring Heathkit. I
suspect (but cannot confirm) that this was one of
their first machines. Here's what the
Operation/Service Manual (copyright 1980) has to say
about this machine:
This Zenith Data Systems Digital Computer is a
versatile, 8-bit microcomputer and professional
video terminal both built into the same cabinet.
The computing functions and terminal operations
are both controlled by separate Z-80
microprocessors. The high quality keyboard, video
display, state-of-the art logic circuitry, and
plug-in accessories make this Computer [Zenith's
The manuals are massively thorough, including a
separate manual just for the built-in video display.
They include complete fold-out schematics, the Z-80
instruction set, circuit description, etc.
The Z89's design is almost classic, and remarkably
functional. The monitor is a 12-inch, 60 Hz black
& white with a single brightness control, and is
capable of displaying high- and low-ASCII characters.
The keyboard is very functional, though a bit mushy
(but still excellent for heavy typing). The keyboard
includes five function keys and a numeric keypad with
arrows, and the system sounds a tone each time a key
is pressed. The beige case is made of a very strong
plastic and is quite heavy.
Technically, the Z89 is an 8-bit Z-80 based
machine running at 2 MHz, with 64K RAM (48K available
to the user, 8K for the system for ROM and RAM and 8K
reserved). The main board contains two Z-80's, one
for I/O and one for actual computing (obviously, the
Z89's other use as a terminal was emphasized).
Storage is on a single, hard-sectored floppy drive
with a capacity of 100K. The Z89 features three
serial ports. Naturally, it runs CP/M 2.2. In
essence, this was a practical, robust business
machine throughout, with none of the fun colors,
sounds or cartridges of home PC's at the time.
The software I have for it today (still running)
includes the word processors Spellbinder from
Lexisoft, Inc., and WordStar (WordStar came on two
floppies, and I didn't like swapping them while
typing so I stuck with Spellbinder); the spreadsheet
program Supercalc; Microsoft BASIC; and a number of
games, including Adventure and Zork (which I still