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H > HEATHKIT / ZENITH  > Z-100/110/120


This mini forum is intended to provide a simple means of discussion about the Heathkit / Zenith  Z-100/110/120 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


Friday 6th April 2012
Big al (St. Joseph Michigan)

An awesome machine. The Desktop 4 contract with the US government really hurt HeathKit. We ended up selling these computers below cost. The H-100 (Z-100) was one of the best computer we made. Baboo Rajaram really knew what he was doing. To bad they canceled the 286 version. Had the wire-wrapped 286 test machine for years.

Tuesday 15th October 2019
John McLaughlin

My very first computer was an H100 with 256K RAM. I joke with students now that their watch has more current computing power. But for its day, it was a great machine. I wrote my PhD dissertation on it with Peachtext word processing software and a Toshiba dot matrix printer.

Tuesday 23rd September 2014
greg greene (Canada)

Best keyboard for writing ever made ! still have mine with 8 inch drives !!!!

Tuesday 23rd September 2014
greg greene (Canada)

Best keyboard for writing ever made ! still have mine with 8 inch drives !!!!

Sunday 14th September 2014
Dale Wilson (Saint Louis, MO)

One of the best things about the Heath/Zenith computers was the technical documentation. Because they published schematics of their design I was able to get the tech sheets for the chips they used and use that to determine exactly how the graphics in the Z100 worked.

Using that information I wrote Palette so I could take full advantage of their design which was far ahead of any other computer at the time. Although Zenith claimed 640 x 200, 8 color graphics, you could reprogram the chip to run 640 x 400 which worked just fine as long as your monitor could handle it.

It was truly sad to see the IBM PC win the marketing war.

Thursday 27th October 2011
dstephens (San Francisco, CA USA)

Started out with a Heathkit H100 remember all too well CPM and Z-DOS. I made the decision when building to not socket the chips and instead hard soldered to the board. Few years back I replaced electrolytic capacitors and resoldered every connection. Still have the system and it still boots up and runs fine.

Software side getting IBM programs to run correctly was a challenge, that taught me I would rather work with hardware than be a programmer, it also gave a me a lot of respect for good programmers who can write "beautiful code" as an art form.

Yes ran video in interlaced mode and managed to get RAM increased to 768K. There were plenty of hardware hacking projects for the S100 bus in Byte Magazine to keep the electronics technician in me happy.

Wednesday 14th September 2011
Renee Rieser (Juneau, AK)

I was nuts about computers (well, Unix anyway, which is what I was using in college) and got engaged to my now husband over Thanksgiving in 1982. I had mentioned to my father that I''d almost rather have an H100 than a "real" wedding. Geez, BEFORE Christmas, an H100 was delivered to our apartment, along with dual 8" drives, a 300 baud modem, JT Turbo Pascal, ...I think we pretty much got the works of what was available both hardware and software. Of course it was a wee bit different than having a scaled down PDP in my living room, which is kind of what I had expected out of it. Soldering all the diodes and resistors onto the motherboard was interesting but more in a paint-by-numbers kind of way than using a breadboard.

I didn''t know BASIC - but I learned. In fact, I learned a whole lot about PC hardware and software over the next few years, although what we had at school were PDPs and Vaxen (and a CDC 6500).

Oh yeah, and I got married in the Tippecanoe courthouse in February 1983, with maybe 7 people in attendance.

Somebody actually STOLE the H100, which I still used on occasion (CP/M) in the early 1990s, when our house got broken into. Heh. I''m sure they didn''t know what they were doing, but losing it that way makes me continue to kinda miss the old beast.

Sunday 15th August 2010
Dan Paladini (Switzerland)

I bought my Z-100 low profile computer in 1983. It was years ahead of its time and was a brilliant computer to learn on. It wasn''t very IBM compatible, although a small percentage of programs for the IBM PC ran on the Z-100 out of the box. Most programs required a significant amount of trial and error "hacking" to run$ what better way to learn about microcomputers! I upgraded the 8088 processor to the hot NEC replacement core, raised the CPU to 7.5 MHZ via a daughterboard and did the wirewrap mod to use those new fangled 256Kbit memory chips to bring the memory up to 768K. Once I got the Video running in interlaced mode, I blew all my friends with IBM PC Color Cards away!
Most of my programming was in Turbo Pascal and, of course, BASIC. This little gem launched my career in computers and kept me happy for the next 7 years until IBM PC Clones finally caught up to its capabilities!

Monday 18th January 2010
Craig Carr (USA)

This was one of my very first work computers in 1985. I started my carreer in the engineering department and this was used for our CAD system. We were running I think ACAD 2.1 or 2.5 on Z-dos.
Zdos was 80$ compatible with MS-DOS. We had huge color monitors on top of the systems. At least 25" displays and 16 colors. It was a great CAD system at the time. And I thought better graphics than the apple computers. I used to create lisp routines that ran within ACAD that would create custom batch that would do plotting as well as call up AutoCad again. Towards the end of the Z-100s, I had two of them in my office and I would start a command on one then swing around in my chair to work on another drawing on the computer behind me.. At this point I was too fast and kept both computers busy .. Fond memories

Monday 8th April 2002
Paul Gautreaux (Louisiana)

My first computer was Zenith Data Systems Z-100 running at 4.77 Mhz with 128 kb on board, but I paid an extra $100 for another 64 bad machine. I bought it used...the guy could not figure out what to do with it. It had two 5.25" floppies and a built-in monitor. I came with about 50-bls of Z-DOS 1.0 manuals that were completely incomprehensable. I paid $2000 for it in 1981 and my wife still has not forgiven me. I had a modem that capped onto the phone with a connection rate of 300 bd. The only programs I had were those I wrote myself and I quickly found out I was not going to make my millions as a program developer...PASCAL still makes my skin crawl. I ended up getting a NORTHGATE 386 machine (backed another winner) and donated the Z-100 to our local library to be auctioned off. Some poor sucker ended up paying $300 for it in 1989.


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