Motivation
So why would I want to undertake an H-500 Computer Lab reproduction? Because most of the projects that I have been working on lately follow the same pattern:
- They are reproductions of cool computer toys and devices from the 60's.
- Have tremendous educational value (when first released and even now IMHO). To that end they usually shipped with well written and instructive manuals.
- Feature unique and noteworthy designs.
- Due to their age they have become rare and thus expensive and hard to get.
- Perhaps most importantly I think that the devices themselves and their designers deserve to be remembered and honored.
- As a bonus for this particular project, I'm Canadian and the H-500s were manufactured in Canada.
So the H-500 is a very good fit for my interests and skill set. Plus I really want one ;-)
Design Goals
With this reproduction I hope to provide the best H-500 Computer Lab experience possible. What do I mean by that? Well...
- Visually my reproduction will be clearly recognizable as an H-500. I will strive to provide an outwardly accurate appearance of the original to the best of my ability and within the constraints of the implementing technologies. Bear in mind that I can't afford one of these so I will be working from images and the kindness of actual owners to provide me with details.
- Operationally my H-500 will perform like the original. A user will be able to work through the experiments in the Lab Workbook without change or issues.
- I would like for this project to be easy to well, reproduce. To this end I will only be using 3D printed parts and readily available components and materials.
- I will try to keep the total project cost to a minimum.
- A complete set of instructions, parts list, and STL files will be posted to Instructables at the completion of this project so that others could make one should they choose to.
So hopefully my H-500 reproduction will look and work like an original, but I can guarantee (at least for version 1) that the very cool PCB with "surface mounted" components used in the original will not be part of the final design in order to meet cost and reproducibility goals.

(Maybe version 2?)
Rocker Man
Well rocker switches is actually the reason that I started considering this project. At the end of my Mostly 3D Printed Rocker Switch project I posted the following:
With a workable and customizable rocker switch in my tool kit now, I'm looking at you PDP-8/I ;-)

A short while later I was looking at the System Source Computer Museum Toy Computers page and I saw the DEC Computer Lab. WOW. This was actually a much better fit for both my interests and skill set. I have made replicas of six of the other computer toys on this page five of which I created myself. And the DEC Computer Lab uses the same rocker switches as the PDP 8/I. Perfect.
Making the Switches
My starting point was an STL version of the PDP 8/I rocker switch that I found at Vince Slyngstad's PDP-8 Stuff page.

I modified it slightly to have a hole at the pivot point instead of a shaft. Then I modeled a "counter weight" to hold the switch magnets and a corresponding base for the "reciprocating" magnets and the reed switches. You will notice that there are two kinds of counter weights. That's because there are two kinds of rocker switches required, a momentary "spring" return for the three H-500 pulse switches, and an ON-ON variant for the eight input switches.

The base has slots...
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The DEC H-500 ComputerLab has a place in the historical record for electrical engineering!
In the late 1960s, in the US, the COSINE Committee was formed to consider how to update the undergraduate electrical engineering curriculum to incorporate digital systems and computer engineering. One of the task forces investigated 'Digital Systems Laboratory Courses and Laboratory Development', part of which was a survey of the hardware then in use at various universities in the US and Canada. (My undergraduate advisor at the University of Delaware, Dr. David M. Robinson, was a member of the task force and presented a couple of breadboard designs, one of which I used when I was a freshman. The textbook we used was written by another member of the committee, Dr. Taylor Booth.) In 1971 they published an 'interim report' which you can find at https://files.eric.ed.gov/fulltext/ED054810.pdf (and if anybody can locate the final report, or a copy with more clear reproductions of the photographs, I'd greatly appreciate hearing about it!)
The DEC ComputerLab is shown in Figure 3-1(b) on p. 13 of the .pdf file and is mentioned by name at the end of the previous page. It is shown again in Figure D-1 on p. 38.
The earlier product, the DEC LogicLab, is shown in Figure 3-3(a) on p. 14 and is described in the middle of the column to the left of the picture.
Appendix B describes some projects built by students. Appendix C describes in some detail a number of the 'homemade' breadboards.
Appendix D shows about ten other commercial products, including (near the end) the now-ubiquitous 'terminal strips' with rows of connected pin sockets on a 0.1" grid, and breadboard systems using them.
Appendix E has a survey which says that 61 schools were using one of the DEC products. The various tables also show the number of computers on campuses from each manufacturer and, for DEC and IBM, the breakdown by model or architecture. (One school still had a PDP-1 in use, and one school had an EAI analog computer in use.)
As I alluded to, we had a few of the pictured 'homemade' units at the University of Delaware. Of particular interest here might be the one in Figure 3-2(a) which used DEC Flip-Chip modules and had the wiring on a removable patch panel (most commonly seen in IBM punch card ['unit record'] equipment) so that you could change the panel to change projects. It was mounted in a rack just to the right of a PDP-8 (straight 8 -- you can see the right edge of the figure 8 on the front panel in the left of the picture) and could be connected to the PDP-8.
I find it interesting that a number of the breadboards had rotary telephone dials! This must have been used to create sequences of clock pulses or enter data; a clever trick that goes all the way back to the EDSAC at the University of Cambridge! (When asked if they used octal or hexadecimal, Maurice Wilkes once said that they used decimal and let the machine do the conversion.)