Reincarnated Return of the HRRG 4-Bit Computer (Part 1)

Maria J. Smith

At times I marvel irrespective of whether I’m the only a person who has interest initiatives that drag on for years, going back again and forth involving the metaphorical again-burner and entrance-burner of my notice span, evolving and transmogrifying as the months transform into months and the months flip into several years and—in the circumstance of some of my creations—the yrs convert into many years.

This kind of has proved to be the circumstance with my Heath Robinson Rube Goldberg (HRRG) laptop, which was originally supposed to be an 8-bit machine when it was 1st conceived deep in the mists of time.

This bodacious elegance is named in honor of British cartoonist and illustrator William Heath Robinson (1872-1944) and his American counterpart Reuben Lucius Goldberg (1883-1970). Both of these gentlemen were being famed for developing illustrations of cunning contraptions whose aims were to execute seemingly easy tasks, but whose realizations executed reported jobs in exceedingly convoluted means.

This all began when I observed a relay-based personal computer established by Professor Harry Porter III, who was a lecturer at Portland Condition University at that time (he may nonetheless be there for all I know). (You can study additional about Harry’s equipment in this article.) I beloved the sound of the relays clicking, and I also liked the way Harry presented his machine in a series of glass-fronted, wall-mounted wooden cabinets. Having said that, I wasn’t so eager on the bundles of wires linking the cabinets collectively.

To be sincere, I’d had the considered of constructing a relay laptop or computer lurking in the back of my mind for some time. I’d even absent so considerably as to invest in some secondhand textbooks on producing relay-dependent logic dating from the 1950s and 1960s. The dilemma was that, in addition to inspiring me, Harry’s development also dampened my spirits since I didn’t want to do a little something that an individual else experienced by now carried out, if you know what I imply.

This is what led me to my primary large-degree strategy of the HRRG Personal computer, which was to make my equipment as a series of glass-fronted, wall-mounted wooden cupboards, like Harry’s, but with every of my cupboards that contains a portion of the computer realized in a distinctive implementation technologies, including (but not confined to) relays, vacuum tubes, discrete transistors, jelly-bean (7400-series) integrated circuits (ICs), mechanical logic, magnetic logic, pneumatic logic…to identify but a several. Also, in holding with the HRRG philosophy, we would do absent with the bundles of cables, applying any inter-cabinet communications via a wi-fi mesh community.

Graphic source courtesy of Joe FarrElectronics Heath Robinson Rube Goldberg (HRRG) computer Max Maxfield

The HRRG 4-bit laptop or computer emulator and printer.

I in fact put a considerable total of assumed into this task, like paying for a variety of goods I planned on employing, such as 1000’s of 1960s teeny-tiny ferromagnetic cores I picked up for a couple dollars from somewhere in Eastern Europe (I prepared to use these to put into action a magnetic logic cabinet alongside with a magnetic core memory cabinet).

Regrettably, I’m a bear of minor brain, as Pooh Bear could say. Also, I have a small interest span and I’m effortlessly distract…SQUIRREL!!! As a outcome, my awareness wandered on to other projects.

After various years’ hiatus, I was introduced to an engineer named Joe Farr. Joe and I share numerous pursuits, together with a adore of retro pcs. Considering that Joe is so central to the existing incarnation of the HRRG, I asked him to send me a handful of words I could use to introduce him, and he replied as follows:

I’m a eager electronics, laptop, and radio novice. The moment I’d finished my (official) education and learning in the 1980s, I commenced my occupation as a laptop or computer programmer for Nixdorf Computers positioned in Manchester, England. Right after quite a few yrs, I relocated south (generally for the better climate), performing with top technological innovation businesses on software package, hardware, telephony, and cellular info programs. Now, immediately after quite a few a long time in the freelance environment, I have settled down in an idyllic place hamlet just outside the house Cambridge in which I tele-commute to my comprehensive-time (working day) work as a senior computer software and components engineer with the London Ambulance Provider.

After far more e-mail conversations than I treatment to contemplate (this was before video clip meeting phone calls grew to become the norm), the HRRG experienced remodeled into a 4-little bit device mainly because we believed that would be additional enjoyable. Also, we identified that a 4-little bit laptop would make extra feeling as an educational software.

The recent concept involves acquiring a process clock cabinet, a CPU cabinet, and a bunch of memory cabinets. The idea is that hobbyists and significant university learners would be capable to construct memory cupboards made up of as small as one 4-little bit word of memory implemented in the know-how of their choice, and that these memory cupboards would then speak to the primary CPU cabinet.

Even better, as portion of this, Joe has made an emulator of the whole program that runs on a Pc. This implies you can first produce a digital memory cabinet that talks to the digital CPU, and later create a physical implementation of your cupboard that talks to the digital CPU (or a actual physical version of the CPU if you take place to have a person).

Picture courtesy of Joe FarrElectronics Heath Robinson Rube Goldberg (HRRG) computer Max Maxfield

The HRRG 4-bit pc assembler.

Just to insert a great big dollop of cream onto the leading of the metaphorical cake, Joe and I described our have assembly language, immediately after which Joe whipped up an assembler. As we see in the screenshot previously mentioned, the assembler alone seems to be like it’s jogging on a virtual Sperry Univac Uniscope 200 info terminal.

So, as you can see, Joe and I put a substantial sum of effort and hard work into this challenge, until…SQUIRREL!!! What can I say, we both equally received distracted with other initiatives, and a layer of dust begun to improve on best of the strategy of the HRRG. And then…

Someday in early 2021 I acquired an e mail from an electronics engineer named Nils van den Heuvel who hangs his hat in the Netherlands. Acquiring operate across some of my previously writings on the HRRG 4-bit personal computer, Nils stated he was interested in building an FPGA-primarily based implementation.

So, Joe, Nils, and your humble narrator commenced to have weekly meetings. There is very little like striving to construct some thing to expose any holes in your layout, and the HRRG was no exception. As a consequence, we have evolved the CPU’s sign-up established and instruction established into some thing that I imagine is really somewhat tasty. I shall share much more on these topics and introduce Nils effectively in my upcoming column. In the meantime, as generally, I welcome your reviews, queries, and solutions.

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