Hobbyists Building Their Own CPUs – The New Stack

Warren Toomey has been involved in some fascinating computer projects. A 2016 blog post describes “Bringing PDP-7 Unix back to life” and another on “on Starting a Unix Legacy Company.”

The messages themselves are part of the incredible journey from a web server from 1994 – which previously hosted a file repository only accessible via FTP. Its content has survived until 2022 and is hosted in the cloud on a spacious virtual machine.

After migrating to the cloud, Toomey writes, “There was no point trying to figure out how to describe the new hardware, since it’s not real”

And now Toomey is involved in another remarkable mission. It maintains a directory of Web pages, each featuring a different in-house processor.

There are 85 different web pages in all, collectively forming a kind of secret society of the world’s most ambitious tinkerers.

The pages were all assembled in the Web Ring Home-Built Computers, where each page connects to another in the series, creating a sort of linked list of web pages. Before Google, a “webring” was a way to collect thematically similar websites. Often they have led to cohesive communities around a certain topic.

Homebrew Computing Web-ring (screenshot from RISC relay CPU site)

Toomey maintains the main directory, offering a thumbnail icon leading directly to each of the 85 pages.

And that’s certainly the case with Home-Built Computers WebRing, where each page represents someone’s beloved personal project – and an inspiring story of determination.

A ring around the world

The webring community continues to grow. Back in 2018 there were only 48 members – so it has almost doubled in the past four years. And while the WebRing’s main page appears to be hosted in Australia, it lists pages from around the world – and in a variety of states of completion.

For example, the RISC Relay CPU (last updated 2018) went so far as to test home-built arithmetic/logic units and register cards for what he describes as “soldering problems.” But it was already able to run “real programs” on its four 8-bit registers. How? By using a Raspberry Pi board which can download a binary version of an assembly language program into the flash memory of the homemade processor.

Screenshot of RISC Relay Processor site (via Homebrew Computing Web Ring)

The data is only 4 bits wide – but that was enough to create an impressive video showing the contraption calculating Fibonacci numbers up to 89. (After which the program begins the calculations again.)

Although this project is based in the Netherlands, much like a real webring, it is linked to other faraway projects, including the site of David Brooks, the founder of Homebrew CPUs WebRing. Brooks’ own site in Australia lovingly describes “the all-TTL machine I built in 1976” – taking visitors even further back in history.

“It all started in 1968, when I was at Bangor University in North Wales…Students punched their own programs (usually in Algol) onto cards or five-track paper tape, and submitted them to the operators. It whetted my appetite for computing. When I left college I lost access to a computer and gradually developed the idea of ​​building my own…. »

More than half a century ago, parts for a homemade computer were hard to come by, but undaunted, Brooks assembled “destroyed hardware from the early 1960s”, including logic boards from an old IBM mainframe computer, later supplemented with logic modules found in London. surplus stores.

Eventually, an I/O mechanism was added – “a surplus WWII ticker”, and later a homemade case was proudly fitted around the finished unit.

And of course Brooks’ page links to another home-built computer’s site – this one in France, sharing details of a home-built processor. designed with field programmable gate arrays.

create magic

The website retired software engineer Bill Buzbee describes a homemade computer built from 200 TTL chips – all neatly connected with thousands of individually wrapped wires.

“My wife and kids may not be impressed with my instruction set design, but all these threads should at least elicit some sort of reaction from them,” the site explains.

Just south of San Francisco, at his home in Half Moon Bay, Buzbee’s multi-year effort became his own monument to the do-it-yourselfer spirit, circa 2004. After installing the Minix 2 operating system, Buzbee could run hundreds of programs on his home computer – while supporting multiple users and multitasking.

It now serves as a web server – and at one time was also a telnet server, hosting classic Unix shell games like Adventure, Eliza, Conway’s Game of Life and Hunt the Wumpus.

The name Buzbee gave to his creation? Magic-1.

Soon, this brought Buzbee to a community of fans. Thousands of people have logged into Magic-1. Between 2004 and the summer of 2007 alone, they left 1388 guestbook messages.”

They came from all over the world – from Austria, New Zealand and Lafayette, Louisiana, all inspired by Buzbee’s quest to learn.

“Ultimately, I wanted a functional and useful machine that I fully understood,” Buzbee wrote on the site.

“Oh, and it had to have a real front panel with lots and lots of cool flashing lights.”

It’s the ultimate hobbyist project, with Buzbee spending the “odd hour here and there” while pursuing his own career as a software engineer.

What kind of person builds their own computer? With a master’s degree in computer science, Buzbee has been everything from a senior software engineer at Transmeta to a senior research scientist at Hewlett Packard Labs.

In 2008, Buzbee became a software engineer at Googlehelping the Android team develop the Dalvik JIT compiler, and in 2018 he became a software engineer at Facebook.

But this amateur project seems just as meaningful. At the end of a biographical web pageBuzbee marvels that his homemade computer “has gotten a lot more attention than I ever imagined a nerdy silly hobby project could get.”

“It also allowed me to finally impress the teenage daughter. Not for making my own computer, but for getting a magazine article about me,” he wrote, referring to how he was. the “star geek”. in the summer 2005 issue of Extreme Tech magazine.

Follow the webring links and the stories keep pouring in, page after page, each offering the almost magical tale of a determined hobbyist who summoned his own material simply by tapping into his own reserves of ingenuity.

The webring is open “to any IT project with an in-house processor”, explains the site’s official charter. It can be a Field Programmable Gate Array (or FPGA) or a chip using transistor-to-transistor logic (TTL) – as long as it’s not a standard store-bought processor.

And the official webring charter ends by sardonically asking if anyone will ever contribute a design built with vacuum tubes.

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