Note #3
Homebrew Computing: The Pragmatists' Revival

Why the DNA of modern digital computing isn't just a distant memory in the pages of computing history.

Rewind the clock to the late 70’s and you may be perturbed to discover, or remember, a time when iPhones did not yet exist, nor iMacs, nor Windows 95, nor the Nintendo Entertainment System, the BBC Micro or even the ZX Spectrum!

Back then digital computers were still in their infancy. Many reading this will be familiar with the ‘Homebrew Computer Club’ - a gathering of computing enthusiasts including the likes of Steve Wozniak who built the first Apple Computer: Apple 1. Or some may recognise the classic ‘Science of Cambridge’ Mk14 - a seminal British microcomputer kit first sold in 1977.

Science of Cambridge Mk14
The Science of Cambridge Mk14

To the uninitiated these machines might now seem archaic or even prehistoric. But they possess something very important: the DNA of modern digital computing.

All digital computers work in the same fundamental way, with basic arithmetic and boolean logic. Downloading a .pdf, watching YouTube, playing ‘Flappy Bird’ - these every day actions all emerge from simple binary operations.

Today’s computers - be it a Raspberry Pi, iMac or Android device - only really differ in the sense that they are miniaturised and highly optimised versions of these early machines. Allowing more data to be processed in one go and at a faster speed. The fundamentals, however, don’t change and that’s important because we should never think of modern computational devices as magical black boxes. They abide by simple and transparent processes, devised by human hands and human ingenuity.

And whilst these sentiments may have been forgotten since the early days of the silicon revolution, it hasn’t been completely lost. Instead the recent convergence of accessible components, the rediscovery of hobby electronics and the reduction in barriers to PCB fabrication are enabling anybody to rediscover the joy and logic behind computational hardware. In fact, a humble homebrew computing revival is already underway!

A great example of this is the work of YouTuber Ben Eater. He has built a programmable 8-bit computer from scratch, inspired by a classic 1977 book by Paul Malvino: ‘Digital Computer Electronics’. The whole project has been documented in a series of YouTube videos. They are a fantastic introduction to computational hardware and digital electronics!

Digital Computer Electronics by Paul Malvino
Digital Computer Electronics (Second Edition) by Paul Malvino

(Consequently, 'Digital Computer Electronics' is also an inspiration for the ARITH-MATIC project. It is a book I own and is a key go-to reference at ARITH-MATIC HQ. I would recommend you buy it – but it’s very difficult to get hold of a copy at a sensible price!)

Another example of the build-it-yourself mentality is from the community. From TTL homebrew CPUs, to logic gate dissections, to retro calculator reconstructions, the world of homebrew computing is very much alive and kicking!

Gigatron TTL Microcomputer Prototype
Prototype of the (excellent) Gigatron TTL Microcomputer by Marcel van Kervinck and Walter Belgers. Source.

The projects at are diverse, not only in the sense of the technology used or the sentimentality some may evoke, but also in the purpose behind their construction. Sometimes doing things ‘just because’ is the very best reason to get making.

Both these channels, along with the archaic beauty of the retro computing era, have been a great source of inspiration in the development of the ARITH-MATIC project and a long-standing aim has been to harness that pioneering spirit in the S1-AU Mk1.

And in doing so, the mission of the ARITH-MATIC project is not only to enable keen enthusiasts to revive a seminal period of the digital computer revolution, but also to inspire an entirely new audience to pick up a soldering iron and discover what computers are really made of.

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Note by: Richard.
Founder of ARITH-MATIC.
July 2018.

To find out more about the S1-AU Mk1 please visit our DIY Electronic Kits page.

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