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8 Bit Spaghetti documents home computer build

8 Bit Spaghetti documents home computer build

Kyle Hovey's homebrew eight-bit computer, built at the TTL level, clearly lives up to his site's name of 8 Bit Spaghetti.

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.

15 Comments

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Shirty 1st May 2012, 11:19 Quote
Proper hardcore :D
mi1ez 1st May 2012, 11:23 Quote
major major kudos!
Fantus 1st May 2012, 11:31 Quote
First Paragraph - "more simpler"

That made my head hurt :P
greigaitken 1st May 2012, 12:24 Quote
somebody needs to make a cable that glows when current flows through it
Tattysnuc 1st May 2012, 12:39 Quote
Sorry to be a Grammar/Typo Nazi but...

"The bulk of the computer is build, with testing taking place now..."

I think you meant "built"

Wonderful project. Can someone clarify if this has been built with a large number of transistors or diodes or something else? Am going to have to go and read the full article and history from scratch me thinks :)
Gareth Halfacree 1st May 2012, 12:51 Quote
Quote:
Originally Posted by Fantus
First Paragraph - "more simpler" That made my head hurt :P
Quote:
Originally Posted by Tattysnuc
Sorry to be a Grammar/Typo Nazi but... "The bulk of the computer is build, with testing taking place now..." I think you meant "built"
Me fail English? That's unpossible! (Both fixed, ta!)
DragunovHUN 1st May 2012, 13:50 Quote
When i looked at the picture i thought "that's almost like something you'd make in minecraft". Then i read the third paragraph and i was like AHA!
Mankz 1st May 2012, 14:42 Quote
Dude... awesome ;)
schmidtbag 1st May 2012, 15:38 Quote
i'd like to see what it can do and how it performs, seems really interesting. of course i'm not expecting much out of it but it'd be interesting to know if it can even run a mainstream OS like linux or DOS.
Gareth Halfacree 1st May 2012, 15:47 Quote
Quote:
Originally Posted by schmidtbag
i'd like to see what it can do and how it performs, seems really interesting. of course i'm not expecting much out of it but it'd be interesting to know if it can even run a mainstream OS like linux or DOS.
Not a chance: for a start, it's an eight-bit system; secondly, its entire output consists of a bunch of Nixie tubes capable of showing a number from zero to nine. While it wouldn't be *impossible* to build a computer capable of running *NIX from discrete components, it'd be prohibitively large and bankrupt you in the processes - assuming running the wiring loom didn't send you crazy beforehand.
Tyinsar 1st May 2012, 20:27 Quote
This gives a whole new (or should that be "old") meaning to "I build my own computers" ;)

Hardcore indeed.
enciem 1st May 2012, 20:29 Quote
I want a 3 Digit Numitron Readout, it rocks.
glaeken 2nd May 2012, 06:28 Quote
Wow, really cool. :) and I thought I was hardcore for making a full adder in my computer architecture class...
slothy89 7th May 2012, 03:35 Quote
Quote:
Originally Posted by greigaitken
somebody needs to make a cable that glows when current flows through it
Considered EL Wire? ;)
Ending Credits 7th May 2012, 10:48 Quote
I agree, computers are a lot more simple at the low level than people suspect. When you break it down piece by piece and use the concept of a 'magic box that does X when I input Y', it becomes very simple.

The problem is, while I could probably spec one myself (having done no more electronics past A-level) designing one becomes very complicated very quickly. There's an awful lot of discrete components even in a simple ALU.
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