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

Sometimes I surprise whether or not I’m the only 1 who has pastime projects that drag on for a long time, shifting back again and forth among the metaphorical again-burner and front-burner of my awareness span, evolving and transmogrifying as the weeks turn into months and the months convert into yrs and—in the case of some of my creations—the many years turn into many years.

This sort of has proved to be the circumstance with my Heath Robinson Rube Goldberg (HRRG) pc, which was originally meant to be an 8-little bit device 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). Equally of these gentlemen ended up famed for creating illustrations of crafty contraptions whose ambitions had been to carry out seemingly basic tasks, but whose realizations performed claimed responsibilities in exceedingly convoluted strategies.

This all commenced when I noticed a relay-primarily based pc created by Professor Harry Porter III, who was a lecturer at Portland Point out University at that time (he may well continue to be there for all I know). (You can learn more about Harry’s device here.) I beloved the sound of the relays clicking, and I also cherished the way Harry presented his machine in a series of glass-fronted, wall-mounted wooden cabinets. Even so, I wasn’t so eager on the bundles of wires linking the cabinets with each other.

To be trustworthy, I’d experienced the believed of developing a relay laptop or computer lurking in the back of my intellect for some time. I’d even gone so significantly as to buy some secondhand textbooks on generating relay-dependent logic courting from the 1950s and 1960s. The difficulty was that, in addition to inspiring me, Harry’s development also dampened my spirits simply because I didn’t want to do something that somebody else had already accomplished, if you know what I mean.

This is what led me to my authentic superior-amount thought of the HRRG Laptop, which was to develop my equipment as a series of glass-fronted, wall-mounted wood cupboards, like Harry’s, but with just about every of my cabinets that contains a part of the laptop or computer understood in a various implementation engineering, such as (but not confined to) relays, vacuum tubes, discrete transistors, jelly-bean (7400-series) integrated circuits (ICs), mechanical logic, magnetic logic, pneumatic logic…to name but a couple. Also, in trying to keep with the HRRG philosophy, we would do away with the bundles of cables, utilizing any inter-cabinet communications through a wireless mesh network.

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

The HRRG 4-bit computer emulator and printer.

I really set a significant quantity of considered into this task, including acquiring several merchandise I planned on employing, these as countless numbers of 1960s teeny-little ferromagnetic cores I picked up for a few dollars from someplace in Japanese Europe (I planned to use these to implement a magnetic logic cabinet along with a magnetic core memory cabinet).

Regrettably, I’m a bear of very little mind, as Pooh Bear might say. Also, I have a quick interest span and I’m quickly distract…SQUIRREL!!! As a end result, my focus wandered on to other projects.

Just after various years’ hiatus, I was launched to an engineer named Joe Farr. Joe and I share many pursuits, which includes a really like of retro personal computers. Considering that Joe is so central to the current incarnation of the HRRG, I questioned him to ship me a couple of phrases I could use to introduce him, and he replied as follows:

I’m a keen electronics, computer, and radio novice. After I’d completed my (official) education in the 1980s, I commenced my profession as a pc programmer for Nixdorf Desktops found in Manchester, England. Right after several years, I relocated south (mostly for the far better local climate), operating with leading know-how firms on computer software, components, telephony, and cellular data devices. Now, after a lot of years in the freelance earth, I have settled down in an idyllic region hamlet just exterior Cambridge exactly where I tele-commute to my whole-time (day) position as a senior program and hardware engineer with the London Ambulance Support.

After much more electronic mail conversations than I treatment to take into consideration (this was in advance of movie conference phone calls became the norm), the HRRG had transformed into a 4-bit machine for the reason that we thought that would be much more exciting. Also, we established that a 4-bit laptop would make much more feeling as an educational software.

The current notion includes possessing a process clock cupboard, a CPU cupboard, and a bunch of memory cabinets. The idea is that hobbyists and large faculty college students would be in a position to build memory cupboards that contains as tiny as a single 4-little bit phrase of memory implemented in the technological know-how of their option, and that these memory cabinets would then communicate to the main CPU cupboard.

Even superior, as part of this, Joe has designed an emulator of the total system that operates on a Pc. This usually means you can initially make a digital memory cupboard that talks to the digital CPU, and later develop a bodily implementation of your cabinet that talks to the virtual CPU (or a physical edition of the CPU if you materialize to have a person).

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

The HRRG 4-little bit laptop assembler.

Just to insert a fantastic large dollop of product onto the top rated of the metaphorical cake, Joe and I described our individual assembly language, immediately after which Joe whipped up an assembler. As we see in the screenshot higher than, the assembler itself appears like it’s jogging on a digital Sperry Univac Uniscope 200 knowledge terminal.

So, as you can see, Joe and I put a sizeable amount of money of effort and hard work into this undertaking, until…SQUIRREL!!! What can I say, we each acquired distracted with other projects, and a layer of dust started to mature on major of the notion of the HRRG. And then…

Someday in early 2021 I been given an e mail from an electronics engineer named Nils van den Heuvel who hangs his hat in the Netherlands. Acquiring run across some of my earlier writings on the HRRG 4-little bit personal computer, Nils explained he was intrigued in producing an FPGA-based mostly implementation.

So, Joe, Nils, and your humble narrator started to have weekly conferences. There is nothing at all like trying to construct a little something to expose any holes in your design and style, and the HRRG was no exception. As a end result, we have evolved the CPU’s sign-up set and instruction established into a thing that I truly feel is really instead tasty. I shall share more on these topics and introduce Nils appropriately in my upcoming column. In the meantime, as usually, I welcome your feedback, issues, and tips.