8 Bit Spaghetti documents home computer build

May 1, 2012 // 11:02 a.m.

Tags: #8-bit #8-bit-spaghetti #cpu #eight-bit #home-computer #kyle-hovey #minecraft #numitron #transistor-transistor-logic #ttl

The increasing complexity of computing is rarely considered a negative thanks to the power it puts at our fingertips, but one hardware hacker has decided to return to a simpler era by building his own eight-bit computer entirely from scratch.

A late night spent browsing Wikipedia's coverage of the concept of Turing machines was all it took to convince Kyle Hovey that he wanted to build his own computer - a concept which hearkens back to the days of the eight-bit home computer, such as the Sinclair ZX Spectrum which recently celebrated its 30th birthday.

If Hovey's name is familiar, you're probably a fan of Mojang's popular build-'em-up Minecraft: Hovey's first tentative steps in building his own 80s-era computing system took place within the virtual world, working with a friend and using the game's flexible infrastructure to create a fully working processor implementation.

A virtual computer wasn't enough for Hovey; using a textbook written in the late 1970s, Digital Computer Electronics by Albert Malvino, Hovey discovered a system architecture, Simple As Possible 1 (SAP-1), which was well-suited to his needs. From there, Hovey has been gathering hardware and building the components he needs to create a fully working, custom computer system.

Hovey's undertaking is not to be underestimated: he's building the system using transistor-transistor logic (TTL) technology, allowing himself no off-the-shelf microprocessors in the build whatsoever. It's as close as the average hardware hacker will ever get to fabricating his or her own processor - albeit without the awkward clean room, and at a fraction of the complexity of a modern CPU.

The original plan to create a four-bit computer was quickly abandoned in favour of a more capable eight-bit system, using Numitron tubes as a display for a retro-themed creation Hovey plans to place in a steampunk-inspired cabinet.

Despite having only started the project in early April, Hovey is already well on the way to completing his first build. The bulk of the computer is built, with testing taking place now ahead of the creation of the final components - controllers for input, output and the write/run logic.

Hovey is documenting the build on the 8 Bit Spaghetti website, and if you take a look at the picture of the computer as it stands now you can see why. If you're interested in how computers work at a very low level, the site is well worth a visit.


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