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This mini forum is intended to provide a simple means of discussion about the Heathkit / Zenith  H-89 computer. If you want to share your own experience or memories, or add relevant information about this system: post a message!

  Click Here to add a message in the forum


Sunday 17th February 2019
Jim Nelson (United States)


Sunday 17th February 2019
Jim Nelson (United States)

Looking for one of these computers to buy. Email me if you have one to sell.

Thursday 22nd March 2018
Jason H. Jester (Earth)

I was very lucky to have a father working in computing in the 1960''s through now. In 1980 he purchased an H89 kit and allowed me to do the entire assembly and learn CP/M. I also messed around in BASIC and Turbo Pascal on it for the summer between my fifth and sixth grades. I had plenty of time on computers before it, but the assembly of the H89 really taught me how systems work. By winter my dad had written some software for a local franchise owner to better manage his operations and the H89 got a new home. I did get to see it in use a few times after. Not until I got an Amiga 1000 did another computer mean as much to me. I have built and assembled many systems of various scales over the years. This will always be my first.

Monday 5th June 2017
Jeff Joseph (Norfolk, VA)

The H89, when compared with the TRS-80s by Radio Shack, could be considered the equivilant of a Model 3½ or "Three and a half". In other words, it was about halfway in power and features between a Model 3 (1980) and a Model 4 (1983). It could go to 64K RAM and the Model 3 was limited to 48K, but the Model 4 had 64K and could go to 128K. The H89 used a 2 Mhz Z80 like the Model 3$ the Model 4 ran at 4 Mhz. (though the H89 could be upgraded to 4 Mhz, the Model 4 could upgrade to 6 Mhz). The H89 had a big 80x24 screen like the Model 4, but the characters were alot fuzzier on the screen. (the Model 3 was 64x16). The keyboard on the H89 had a much better feel than the Model 4, though. Both could run CP/M, but the Model 4 had its own large library of TRSDOS 6 programs and ran all Model 3 programs as well. There was a company that made a one megabyte RAM board, and it was easy to install because it went into the H89''s card cage. The Model 4 could be upgraded to one megabyte, but you had to do alot of soldering on the CPU board. The H89 RAM board could be used only as a RAMdisk$ the Model 4 board had drivers which permitted its RAM to be used as general-purpose expansion memory for TRSDOS applications through its standard @BANK supervisor call.

Tuesday 25th February 2014
James Starbird (Van Buren, Arkansas)

I assembled a H89 whilst Principal at an elementary school. Wrote a program to number-crunch attendance for the dreaded Quarterly Report. The Superintendent saw it, and bought a TRS 80 for his needs. Mine was the first. Also played the horse race game on it, and figured out how to rename the horses after the School Board members. Computers for teaching came rapidly after this beginning.

Wednesday 2nd May 2012
Linda Adams (Northern Virginia)
Linda Adams'' Blog

This was the first computer my father bought so he could research how to do fusion through computer programming. My brother designed a Pacman program on (it was very primitive in the graphics area), and I did writing. It had to be booted up with a disk, and in those days, software did not have backups. One time I was saving a file, and it was too big for the disk, for the computer abandoned it!

Tuesday 20th March 2012
Sergey (Moscow, Russia)

Wanted this computer. I will pay any postage costs!


Saturday 6th November 2010
Brian Gregory (UK)
My Homepage

I was given one of these by one of my lecturers when I finished at university in 1983. Great fun. I modified it to so you it could switch to run at 4.096MHz (double speed). It had no soft sectored controller and Heath had stopped making them so I made myself one on veroboard, but using a more modern (but compatible) controller chip to make it easier to build. Later I added a RAM disk by, among other things, replacing all the old 16Kb RAM chips with 8 more modern 256Kb chips. I stopped using it once I got an Amstrad PC2286 and later sold it for £50.

Monday 12th September 2005
Alexander P. (USA)

for those who have heard of the Hero 1 robot, i believe this was one of the terminals you could use to program it, right?

Tuesday 18th November 2003


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