VCF East 2021: Preserving Heathkit’s 8-Bit Computers

To say the Heathkit name is well known among Hackaday readers would be something of an understatement. Their legendary kits launched an untold number of electronics hobbies, and ultimately, plenty of careers. From relatively simple radio receivers to oscilloscopes and televisions, the company offered kits for every skill level from the post-war era all the way up to the 1990s.

So it’s hardly a surprise that in 1977, seeing the success of early home computers like the Altair 8800 and IMSAI 8080, Heathkit decided to join the fray with a computer kit of their own. But by that point the home computing market had started to shift from a hobbyist’s pursuit to something the whole family could enjoy. Compared to the Apple II and TRS-80, both of which also launched in 1977, Heathkit’s machine seemed like the product of a bygone era.

While it might not have gained the notoriety of the microcomputers it was designed to compete with, the Heathkit H8 is certainly not forgotten. Tucked away in a corner at the 2021 Vintage Computer Festival East was an impressive exhibit dedicated to the Society of Eight-Bit Heath Computerists (SEBHC) called Heathkit: Keeping the Legacy Alive. Presented by Glenn Roberts, this collection of original and modern hardware demonstrated the incredible lengths to which this group of passionate Heathkit owners have gone to not just preserve the memory of these often overlooked computers, but to continue to improve upon the kit’s unique design.

No Mere Clone

While the Heathkit H8 might have been designed as a contemporary to the Altair 8800, and used the same Intel 8080 CPU, it was by no means a clone like the IMSAI 8080. In perhaps the biggest departure from common microcomputers of the day, the H8 didn’t use the S-100 bus. Hastily thrown together and based on military surplus 100-pin edge connectors, the S-100 bus had a number of known issues, so Heathkit decided to design a simplified 50-pin backplane design they called the Benton Harbor Bus.

Installing the H8’s backplane

The backplane was mounted on the right hand side of the H8’s enclosure, and could accommodate ten angled expansion cards. The first slot was naturally taken up by the front panel hardware, with the CPU board occupying the second. In the default configuration this left a generous eight additional slots for expansion purposes, though the card in the last position needed to be of a reduced length or else it would hit the power supply.

Operationally, the H8 also differed significantly from its competitors. The front panel did away with the distinctive binary toggle switches and LEDs of the Altair, and replaced them with an octal keypad and seven-segment LED displays. This allowed users to much more rapidly enter programs and examine memory addresses, although the address notation was somewhat less intuitive. That said, the H8 actually had a 1 kB ROM that contained enough code to boot the machine into a functional state, so the user didn’t need to key in a loader each time they started up like they would on earlier S-100 microcomputers.

Clearly, Heathkit wasn’t just looking to copy what the competition was doing. They had some very interesting ideas about how a microcomputer should work, and made a number of improvements over the defacto machines of the day. But there’s always room for improvement.

Remastering a Classic

Since the H8 came in kit form and included complete schematics, members of the SEBHC have been able to create modern replicas that roll in various tweaks and improvements. With community developed PCBs and documentation, it’s possible to create a functional Heathkit H8 without having any of the original hardware.

An H8-2000, with IDE drive and ATX PSU.

Depending on which generation of PCBs you use, these are referred to as H8-2000s or H8-2020s by members of the community. Without the benefit of the original enclosure these machines can end up looking rather industrial, but the aesthetics are largely dependent on how far the person building the system wants to go. Of course, if you’re fortunate enough to have an original H8 (or at least, parts of one), you can augment it with the newly developed components and expansions for the best of both worlds.

Members of the SEBHC such as Norberto Collado have developed an incredible array of expansion cards to fit the H8, such as memory upgrades, IDE controllers, networking interfaces, a USB controller that supports Mass Storage devices, and even a new CPU board that uses the Z80. A properly outfitted H8 has the potential to be a retrocomputing dream machine.

Glenn put two such H8s right at the head of the table to grab the attention of passing attendees, as even to the uninitiated, it was abundantly clear these computers were the result of some blended design. Seeing the vintage enclosures outfitted with modern ATX power supplies and newly-manufactured expansion boards, show goers couldn’t help but be curious. Particular attention was paid to what Glenn calls “Big Blue”, a H8-2020 outfitted with a startling blue LED display and lighted keypad, a gorgeous blend of 70s simplicity and modern style.

Copying the Competition

In an effort to catch up to newer machines from the likes of Apple and Tandy, Heathkit soon introduced a new desktop machine, the H89. It was based on the Z80, combined a 12 inch CRT display and disk drive into one unit, and was available in both kit and pre-built forms. The end result was something that looked a lot like the TRS-80 Model III, and nothing like the H8 that came before it.

Set up right next to Glenn’s table, Alex Bodnar brought his beautiful H89 along as part of an exhibit he called Adventure 1.0 on the Heathkit H89. As the name implies, his machine was set up running the CP/M version of the text adventure off of the original floppies offered by the Heath Users’ Group.

Unfortunately, Heathkit’s days in the computer game were numbered. Not long after the release of the H89, the company was purchased by Zenith, who in turn rebranded the H89 as the Z-89 and ended sales of the kit version. The Z-89 went through a few revisions and stayed on the market until 1985, but the Heathkit name would never again grace the front panel of a computer.

For a New Generation

Despite Heathkit being exceptionally well known brand among electronic hobbyists, relatively few are familiar with their brief foray into the computer market. Several attendees came away from Heathkit: Keeping the Legacy Alive surprised that a company they knew so well had developed and marketed multiple computers that they’d never even heard about.

The Heathkit H8 might never have gotten the chance to star opposite Matthew Broderick back in the 1980s, but through the efforts of the Society of Eight-Bit Heath Computerists, this vintage computer seems well positioned to get a second chance at life. The fact is, you can build a brand-new H8 today that’s more capable and more reliable than the original from 1977. So whether you’re looking for a unique electronics project or want to explore the world of retrocomputing, a Heathkit might be just what you’re looking for.

35 thoughts on “VCF East 2021: Preserving Heathkit’s 8-Bit Computers

  1. I’ve got an old HeathKit H8 and associated documentation. Doesn’t currently work and it’s been years since I’ve done anything with it, but it was a quirky little thing to try to program. IIRC despite having a 16-key keypad, most of the programming was done in octal. But not all of it. Weird little machine but cool.

    1. I have one as well, inherited from my father. Three drives, documentation, and some software, working but no idea what to do with it. I guess I should try selling it online somewhere.

  2. Timing is everything. Surely when they started planning the H-8, it made sense. I assdumeitstarted long enough before that they had no knowledge of the three all in ones arrivong to market that year.

    When Heathkit launched into home computers, they had quite a spread in Kilobaud. It wasn’t just the H8, and the H11, but a bunch of things to go with them. They didn’t dip their toes, they plunged in.

    The H11 of course used the LSI-11, so it was more like packaging

  3. One big thing that Heath brought to the table were their superb manuals, which documented EVERYTHING. They even supplied source code for their software. You could build, maintain, and even upgrade them yourself. That’s why they developed such a thriving user community (the most important peripheral for a computer is its user group).

    The H8 and H89 weren’t their only computers. There was also the H11 (a DEC PDP-11 clone), the Z-100 (an S-100 family of computers), and the Z-150 series of true PC-clones, several HERO robots, and a series of trainers using the 6800 family.

  4. Not snark, genuine enquiry.

    What did you actually DO with the H8 / Altair generation of computers? Were they considered mainly as programmable calculators? What function did they provide in an academic/business/home setting?

    Thanks!

    1. At the time, the H8 was as good as it got. The initial thrust was to have a computer, an end in itself. But that helped to define what they could be used for. If nothing else, people wanted to legitimize the purchase so they’d cook up uses, like keeping recipes in the kitchen.

      You couldn’t do much at first, very limited RAM and cassette or paper tape storage. But soon, if you had money, there were floppy drives.

      The H8 lagged compared to the Apple II (and the TRS-80 and Commodore PET), that all came out in 1977. So a lot of change in 2 years, and a lot of change to come.

      There was an H8 at a friend’s college by 1978, I can’t remember if it was official or owned by a club. That was still exploring. They wanted a terminal, I suggested buying a TRS-80, which was.overkill, but at the time probably cheaper than a dumb terminal.

      People were using home computers in business, though initially mostly hobbyists. I recall someone keeping inventory, others doing design so yes likely fancy calculators. The Heathkit H11 was expensive, but cheap for a PDP-11 system, so if you had the money, yiu couod really go places.

      I got my KIM-1 in 1979, an end in itself,as was my OSI Superboard in 1981. All that I could afford. In 1984, I got a Radio Shack Colour Computer, and a floppy drive, so I actually replaced my typewriter then. Before the floppy drive, I couldn’t do anything practical, and didn’t have the money before then.

    2. Certainly this era of computers made it into laboratories for automation and instrument control. They also made it onto desks for number crunching that programmable calculators just couldn’t do like successive approximation to solve for problems that did not yet have an equation (Modelling). The notion of computers being used for recipies and games back then was a construct to get the public used to computers. A bit like the later hype of a 386 computer equipped with multimedia which was just terrible but it got developers working on it and got the public ready for the next step. The H11 of that early era however was tried and tested computing power that could do some serious real time data collection and control in the lab. The LSI-11 running RT11 was used in neuroscience labs for realtime measurement and collection. As soon as floppies entered the market databases, spreadsheets, data management became practical and world changing in my opinion. The early computing was the launchpad for aspiring electronics engineers/techs/programmers to embed the very same processors into just about every part of our life. security systems, SCADA, appliances and more.

      1. Computers in kitchens was in an early issue of Byte, maybe the first six months. It was very niche still. But it’s an example of trying to find a use.

        It was a period of growth where “need” wasn’t part of the equation. Some of us had wanted their own computer before it was feasible, so just ringing the bell caused the initial sales. It generally took some work to be an early participant. But that created the foundation for later. I can’t imagine it happening if it started with a fully ceveloped product and some well defined need. It needed that simmering.

        A lot of the early buyers were interested in electronics. So they could jump in, but not.much to show it off. Hence another reason for BASIC, you couod do simp!e things like hunt the wumpus and hangman. In 1976, Peter Jennings had a successful chess game for the KIM-1, all of 1K of RAM. One of the first programs I typed in was Moon Lander. And if you had BASIC, there was David Ahl’s book of BASIC games.

        No, they weren’t fast or graphic, but it was easier to type in a game than something more complicated, and no need for floppies to save the results.

    3. Much the same things we do with computers today. Professionals used them for word processing, accounting, inventory, data acquisition, programmable controllers, etc. For hobbyists, it was mainly for games, writing your own programs, and developing your own peripherals.There was no web of course; but there were bulletin boards that you communicated via modems.

      Asking what people did with computers 40 years ago is a bit like asking we did with cars 40 years ago. Even though the technology was different, people used them pretty much just like they do today.

    4. My H8 was hooked up to an H19 terminal and H17 floppy drives, so the experience was similar to using a TRS-80 or an IBM PC. On HDOS there were Microsoft BASIC, the less capable Benton Harbor BASIC, lots of video games using the semigraphics character set (and the H8’s built-in speaker), text editors called PIE and SCRIBE, text formatters similar to nroff called TEXT and RUNOFF, and text files traded on disk at user-group meetings, including porn. For electronic engineering, you could do a lot of calculation and simulation in BASIC that would have been really hairy on a programmable calculator, although its ability to plot graphs on the screen was pretty limited.

      I was a kid, so my favorite use was the games (and the porn). My favorite games included Munchkin (a Pac-Man clone), Invaders, SEABATTL, A Remarkable Experience (a puzzle-solving text adventure similar to ADVENT or Zork), CASTLE, and Star Trek, where you would fly around shooting Klingons with your phasers and photon torpedos and try not to fly the Enterprise into a star. Other games I played included Lunar Lander, Hammurabi, Towers of Hanoi, Reversi, chess, and a significantly enhanced non-turn-based version of the “robots” game in the bsdgames package.

      Under CP/M there was WordStar, a mostly WYSIWYG word processor with only a few nroff-style dot commands left, and SuperCalc, a spreadsheet. There was a huffman-coding utility called SQ[ueeze]. Later I installed MODEM7 under CP/M and dialed up BBSes with a modem, and I could upload and download files with XMODEM. Sometimes, though, I couldn’t download a file unless the BBS sysop was kind enough to break it up into pieces that were smaller than the (100KiB) floppy disks.

      Despite the availability of PILOT, effectively everything that wasn’t written in BASIC was written in assembly language; both HDOS and CP/M came with an assembler, a linker, and a library facility to pull only the library routines you needed out of a library. Later on BDS C and Turbo Pascal brought high-level languages to the platform, but they were too late and not competitive in performance with assembly language or beginner-friendliness with BASIC. Unfortunately, I never learned how to program in assembly until much later, on the 286.

      Presumably some people used them for real-time process control, circuit testing, and stuff like that, but I never did. My electronics kit was a disjoint hobby, which in retrospect is a shame.

  5. “The Z-89 went through a few revisions and stayed on the market until 1985, but the Heathkit name would never again grace the front panel of a computer.” This isn’t quite right. Heathkit as a mark wouldn’t be shown again, but Heath and Zenith were. Zenith released the Z-100, and there’s a Heath kit version named the H100, which was a S-100 based computer, around the same time as the IBM 5150, with both an 8088 and an 8085. It’s worth noting that the H89 is basiclly the H19 terminal with a Z80 computer inside, the chassis and case are the same for the most part.

      1. I had an original H89 from National Technical Schools (one of those pesky cards in the early magazines) Later two H19 terminals later installed with Morrow
        surplus motherboards purchased from a surplus warehouse in Oakland, CA.

        Thank you for preserving history

      2. Yep, shortly after I moved to Florida my H89 got zorched by lightning. Terminal was fine, but the CPU board was cooked. I pulled it out, rigged up a bracket, and stuffed an Ampro Little Board (that I had laying around from a pre-move BBS I ran) into, and ran it like that for another 15 years. For the most part, got me thru college. :)

    1. What are you trying to say with this comment? The author says the Heathkit name was never used again, which you appear to agree with. So who cares about what Zenith did after that?

      They may have put Heath on other machines (I seem to remember at least a Heath 286 back in the day) to try and bank on the goodwill the community had, but that’s not the same thing.

      1. I think it’s a distinction.

        The company was named Heath Company, not Heathkit. We all refered to it as “Heathkit”, but that was a secondary name. At some loint, they stopped putting “Heathkit” on the products, just “Heath”. Not unlike Radio Shack moving to “Tandy” over time.

        I just looked at a late 1987 catalog, and they had products labelled “Heathkit”, but others were labelled “Heath” or Heath/Zenith.

        It looked like test equipment, at least the fancier stuff, was Heath, as was the computer equipment.

        The core company changed hands a few times. Daystrom bought it in 1954. Schlumberger bought Daystrom in 1964. Zenith bought the Heath company in 1979. In 1989, Bull bought the company, and it was sold again in 1995, and 1998.

        That surely impacted the company as did the changing electronic scene.

      2. I’m saying that it seems to imply this was the last computer the company made, when that’s not true. the Z-100 (and H100 by extension) are pretty interesting, and omitting them from the history of Heath/Zenith is a bit weird. That’s all.

        1. In the early eighties, there was that transition phase. Godbout and others offered S-100 bus boards that had both an 8085 and an 8088 or 8086. So you could move forward, but also fallback to a larger software base. Some of this happened before the IBM PC and msdos, and then ran in parallel for a few years.

          Heath had theirs, an integrated package rather than just a board to add to an existing system. And certainly Jerry Pournelle wrote about it in his column in Byte.

          Looking back, everything happened so fast, but at the time it unravelled slowly. We were living through it.

    2. I first bought the H19 kit, ran it as a dumb terminal for a while, then bought the Z80 card to upgrade the H19 to
      an H89, added dual internal floppy drives, and had a great CP/M and Heath BASIC computer, which served me
      well for many, many years.
      The one weak spot was the molex connector for the power supply card. As an H19, the current drawn thru
      the connector was fine, but after H89 conversion, the DC output pins would overheat, discoloring the plastic
      connector shell, and eventually the pins themself oxidized, causing poor DC for the terminal and CPU boards.
      The remedy was to remove the molex connector entirely, and solder the DC cable wires directly to the
      power supply card DC output traces.
      Voila! no more problems.

      1. I repaired a bunch of “roasted molex” connectors on a piece of 30+ year old industrial equipment earlier this year the same way you did, by removing the connectors and soldering the power leads directly to the backplane of the card cage. It’s interesting how enough corrosion developed over time to increase the connector’s resistance to the point where it became a heater.

  6. The family had an H89 kicking around my dad built which used to run the database and document-formatting for my mom’s public-speaker registry business. I think we got Lunar Lander to run on it?

  7. The H89 came about before the TRS-80 Model III.
    It ran HDOS and CP/M
    If I remember correctly, they continued to use Octal for compatibility with the H8 (8080). I believe some commands were common to both for software compatibility.
    I made a couple of games on it using the H19 commands to simulate forward motion by using an insert character. Many, many years ago.
    The modem was an acoustic coupler and noise on the phone line would sometimes make the modem misinterpret the keyboard lock out Escape sequence. Made a dumb terminal program in Tiny Pascal to filter that out.
    Good memories

  8. One thing not in the images, but of note at the exhibit was the beautiful aesthetic but terrible design of the H9 terminal. Every Heathkit computer fan who’s worked on one says it’s a bear, and not worth how pretty it looks. Just go for the H19 instead (as we can see here)

  9. What were they good for? In 1978 when I bought a new H-89 kit, it was to learn more about microprocessors. Outgrew the intel SDK-80. Self taught, led to a career in software engineering that lasted 25 years. Favorite tools were ASM and C languages with a good text editor. Wrote and sold some hobby stuff for the Z-100, H-89, H-8 series. Also used the 89 as a cheap development machine to create ASM software for industrial machines of the time, rack mounted 8080 based stuff like BLC-80 from National. Fun times! A fellow from the local user group was an economist for Ohio Bell. He justified an H-89 because he could run a spreadsheet on it, eliminating lots of mainframe time and charges.

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