Heathkit H8

Performa

Member
Thanks to @DeanG the WCC has managed to add a vintage Heathkit H8 Microcomputer to the fleet- and this machine is in a league all it's own!



I'll preface this by saying that we haven't powered anything on, and probably won't until we've managed to ascertain that it's absolutely safe to do so. We've consulted some experts already, and are actively seeking input from more knowledgeable people on how to best repair, restore, maintain, and display this beautiful piece of hardware, as it's decidedly more unusual than most consumer-grade computer systems of the era. If you know more about these systems, feel free to chime in here or contact me directly using the message function here on the site.

This is going to be an extensive thread with a lot of pictures, discussion, and (soon) all the archives and scans I've been working on saving so that we can all have them for posterity.

I'm really excited, this is going to be a very exciting project!
 

Performa

Member
Some history!

Heath was an electronics manufacturer from Benton Harbor, Michigan, that sold all sorts of things in "kit" form, where the end user would assemble them. These were marketed under the brand name "Heathkit" or "Heath-Kit" emphasizing that these were for the user to build themselves- though Heathkit would sell "prebuilt" units at a greater cost for those willing to spend more to get them- though these were still hand assembled by their team in Benton Harbor, and not in a true "factory" setting as other computers were.

The Heathkit H8 was a computer roughly analogous to the Altair 8800 and other S-100 computers of the era, though it used the "Heathkit" bus which used pin headers rather than card slots to connect the various cards and components together. Paired with a terminal and some form of BASIC or CP/M, these computers could do a variety of things. These came equipped either with an Intel 8080 processor, with the option for a Zilog Z-80 later. (This one has the earlier Intel 8080 board.)

Expensive and technically challenging to build, the H8 (like most computers of it's time) were significant investments, and were generally employed by governments, larger data-oriented businesses, and a few very dedicated hobbyists.

Wikipedia article HERE.
 

Performa

Member
We are extremely lucky for a number of reasons. Firstly, the system is in immaculate condition- while dusty, there was no rust, serious corrosion, or damage as far as I can tell. The system includes the terminal, also in great shape, and a tractor-feed thermal printer of some sort. In the greatest spot of luck, the system also includes virtually all of it's original documentation (including assembly schematics) and the original software cassettes!



I'll have all of this archived and backed up, and then out to the Internet Archive and here so anyone who ever might need it will have it. That will all be done very soon!
 

Performa

Member
A quick look under the hood:







I plan to fully disassemble and deep clean this machine, but I'm waiting to hear back on a couple capacitor questions before I proceed. If it's not obvious, I'm very worried about possibly damaging this system, so limiting the amount of handling these cards and components get is a priority.

Once it's cleaned up though, these cards should be a dazzling sight to see. 😗
 

Performa

Member
Here's a look all around the Heathkit H8 Computer itself:



Made of metal, plastic, and wood, it weighs right around 30 pounds. Most of the weight is situated in the back left corner, where the power supply lives though.



You could run the entire computer just off of this number pad and digit display. But I can't imagine too many people would prefer this over the terminal option.



The display behind this red plastic window.



The number pad after some cleanup. The keycaps didn't want to budge, so I didn't push them. Instead, I cleaned around them using a clorox wipe wrapped around a plastic knife from McDonald's "Big Breakfast" pushed gently between to get all the dust between them. While not perfect (and I did try it a few more times after this photo) it is much better now.



The back of the computer has a number of fixed cables coming out. There are four mini audio jacks, the larger gray "serial" cable (leading from the square connector on the back), the black power cord, and a rainbow ribbon cable that leads to a parallel port- almost certainly to control the printer.



A closer look at the machines' single "port" on the back.



Serial number stickers- while the sticker on the bottom left is for the computer itself, all the other stickers coincide with a card in the machine- indicating that they may have been added sometime later.
 

DeanG

Well-known member
Awesome pictures and exciting additional finds!
This computer has an Intel 8080, the predecessor to the 8088/8086 in the XT machines, and a very early Intel chip: https://www.tomshardware.com/picturestory/710-history-of-intel-cpus.html
It's a collector piece in itself, and I'm glad this system wasn't pieced out on the ebay market.

Now to find an Altair...or at least an 8800 based machine :D
 

Pezdude

Active member
Awesome pictures and exciting additional finds!
This computer has an Intel 8080, the predecessor to the 8088/8086 in the XT machines, and a very early Intel chip: https://www.tomshardware.com/picturestory/710-history-of-intel-cpus.html
It's a collector piece in itself, and I'm glad this system wasn't pieced out on the ebay market.

Now to find an Altair...or at least an 8800 based machine :D
That would be such a fun computer to have on display!
 

Pezdude

Active member
I can’t wait to see H8 up and running! Very cool history about it too. A computer relatively made so close to us and made pretty early on in personal computer history. There is something about computers of the 70s that you don’t get with some other ones. Maybe it’s my love for disco music talking or just how early on in computer history it’s in, but I think computers from that era are just so interesting!
 

Performa

Member
I've messaged a few people about this find, but wanted to dig deeper before I posted anything about it. Alas, my leads have all vanished, and I don't know any more, so here it is!

We've found a few notes, and other indicators that this computer once belonged to or was used by Dr. Carl Alexander, an employee of the Cargill company at their research farm in Elk River, Minnesota. Information about him is hard to come by, and even harder to verify- though one source credits him as the co-inventor of the "Pigloo" in the early 1960's, while another source indicates he won a prize for work in poultry in 2015. However, it's hard to say, as we still know virtually nothing about him.



One of several notes found in with the cassette tapes and binders. No idea what they could mean.



Worn sticker on the corner of one binder. Appears to be the old Cargill logo used from 1952-1998 (as seen HERE).



"Alexander" written in pencil on the manual for the H9 terminal.



One of many "LP" tapes, none dated later than 1979.



The sole photo of Dr. Carl Alexander, found on an article on the Cargill website (HERE) about the Cargill Animal Nutrition Innovation Center in Elk River Minnesota, which is still operational today.
 

Performa

Member
The Heathkit H9 Terminal:









This last photo I used my tried-and-true between-key cleaning method of a cleaning wipe wrapped around a plastic knife (graciously supplied by McDonalds many moons ago), and it does show a considerable difference. This unit definitely has a more "smoky" smell than the H8 computer, so it'll need the deepest clean to be really nice again.

The keycaps aren't printed- they have stickers on each key, which pretty well rules out my usual keycap cleaning process. They're also on there really good, and I worry I could damage something if I try to pry them off by force. I am surprised that all this time later, the keys are still in good shape- it must have been extremely well cared for before it came to us.
 

Performa

Member
Inside the H9 terminal! The top portion is held on with 4 screws, while the panel covering the keyboard is held in with two screws and two small bolts. Unfortunately, all deeper levels of work require the unit be partially disassembled.







That's a big capacitor.



I/O process board



Video process board.

Note the internal speaker and the errant blob of solder on the cage around the unit's main RAM board.
 

Performa

Member
Last but not least, the Heathkit H14 printer.







I'm pleased to say most of the splotches and blemishes came off with a little baking soda and scrubbing.





Opens up very much like a hood of a car. It seems that the user would have to dig in here quite a bit to adjust settings and change ribbons.







Appears to be the CPU for this thing, though the number pulls up a wide range of address-specialized CPU's Motorolla was making at the time.
 

Performa

Member
Oh, and a look at the ribbon thread mechanism for the Heathkit H14 printer. It keeps the ribbon feeding one direction when applied.

 

Performa

Member
An immense thanks to Dave at the VCFMW show, who took some time to walk me through his Heathkit H8 setups. He's been fixing these for a long time, and knows them inside and out. His insight has been invaluable, and guidance will lead us to getting our own Heathkit H8 system up and running I believe.



His first and most simply advice was to get the documentation, read and understand it, and expect some of the ancient tantalums to fry and need replacing. The unit on the left in the photo above is (basically) identical to the system we have at the moment, while the system on the right is a collection of parts and aftermarket additions. I have plenty of reading to do when I get back, and from there I'm confident we can start the testing process. It would be very cool to see this one at a show in some capacity!
 

Performa

Member
Alright, here's that video of what @PS2it and I did to get it this far. Apologies for the video quality, it was framed to catch a big "poof" when the caps were expected to blow, and they didn't, and I didn't adjust things. Hopefully a mistake I'll only make once... 😑

 

Pezdude

Active member
Alright, here's that video of what @PS2it and I did to get it this far. Apologies for the video quality, it was framed to catch a big "poof" when the caps were expected to blow, and they didn't, and I didn't adjust things. Hopefully a mistake I'll only make once... 😑

Great video guys! Hopefully the troubleshooting won’t be too troublesome. Super cool that someone at VCF was able to give some insight. I can’t wait to see it in person!
 
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