Programmable computer built from a humble ATtiny84

attiny84-computer

Here’s a way to play around with simple computing concepts without going too crazy with the hardware side of things. [John Eisenmann] calls it the DUO tiny. It’s a programmable computer based around the ATtiny84. He wrote the operating system himself, building in a set of commands that make it quite functional, but allow the user to manipulate or even write the programs using the four button interface. Editing and running programs (which include some games) is demonstrated in the clip after the break.

The three major components used in the system are the ATtiny84, and EEPROM chip with 64 KB capacity to hold the programs, and the 102×64 pixel LCD screen seen above. The project began on a breadboard, but as he brought each part into being it transitioned to a strip-board prototype and finally this fab-house version.

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World’s oldest functioning digital computer reminds us of a telephone exchange

This is the WHICH, the Wolverhampton Instrument for Teaching Computing from Harwell. It is the oldest functioning digital computer and thanks to a lengthy restoration process you can go and see it in person at The National Museum of Computing in Milton Keynes (Northwest of London in the UK).

The system was first put into operation in 1951. It’s function is both familiar and foreign. First off, it uses decimal rather than binary for its calculations. And instead of transistors it uses electromechanical switches like are found in older automatic telephone exchanges. This makes for very noisy and slow operation. User input is taken from strips of paper with holes punched in them. As data is accumulated it is shown in the registers using decatrons (which have since become popular in hobby projects). Luckily we can get a look at this in the BBC story about the WITCH.

According to the eLinux page on the device, it was disassembled and put into storage from 1997 until 2009. At that point it was loaned to the museum and has been undergoing cleaning, reassembly, and repair ever since.

[Thanks David]

Breadboarding a 4-bit ALU

[TGTTGIT] recently took the plunge and decided to build his own computer using logic chips. He just completed a 4-bit ALU which can compute 18 functions. It took a long time to get the wiring right, but in true geek fashion his build was accompanied by an alternating Chapelle’s Show and Star Trek: TNG marathon playing in the background.

This project is the stepping stone for a larger 16-bit version. The experience of wiring up just this much of it has convinced him that an FPGA is the only way to go for the future of the build. But since he had already ordered the chips it was decided that the only thing to do was to see this much through. He used the truth table from The Elements of Computing Systems for the design and posted several times about the project before arriving at this stopping point so you may be interested in clicking through the other post on his blog. There’s also a lot of other TTL computer projects around here worth checking into.

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Computer desk… literally

This piece of furniture begs the question, why think of a desk and a computer case as separate things? It combines Ikea furniture with electronic hardware to create the ultimate command center.

First the obvious parts: there’s a nook for the computer case that hangs just below the desktop off to the side, and the twin displays are mounted front and center. The divider between the cabinet pieces was cut away to allow the monitors to be wall-mounted. But things start to get interesting to the left of those monitors. You can see a series of dial displays in the door for that cabinet. Those meters were sourced from the MIT Flea Market and after a bit of alteration they display CPU load information fed to them by  an Arduino board. This also drives some LED strips which are mounted behind the frosted glass panel that we guess could be called a back splash. The heavier the load, the better the light show.

All of the power management is taken care of in the cabinet to the right of the monitors. The top row hides a printer, external hard drive backup system, and several gaming consoles. Heat will be an issue so exhaust fans were added to each of these partitions. They’re switched based on a temperature sensor in each. It’s a lot of work, but the outcome proves it was worth it.

[via Reddit]

Calculating with 3D printed gears

Here’s a 3D printed electromechanical computer built by [Chris Fenton] over at NYCResistor. It uses plastic registers printed on a Makerbot, a bunch of pogo pins, and business-card sized punch cards capable of storing 32 bits of instructions and data.

In case you’re wondering, this isn’t the first time we’ve seen [Chris]‘  FIBIAC. Since the last update, [Chris] managed to get a program that walks through the first three digits of the Fibonacci sequence. There’s really no limit to what the FIBIAC can theoretically do, but with only three registers he’s limited to calculating the first three digits of pi.

With more registers, [Chris]‘ computer could be expanded, but each register takes about 8 hours to print. We’re sure [Chris] would gladly accept any donations of additional 3D-printed registers, so if you’d like to make a few of these gear registers you can get the files on Thingiverse.

As a proof of concept, [Chris]‘ FIBIAC is amazing, but it doesn’t live up to its intended design. The punch card format [Chris] created is capable of storing 8 registers, and the registers themselves can be expanded far beyond their current 3-digit width. Still, it’s an incredible build and has the bonus of being easily expandable thanks to a very clever design.

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Build an 8-bit TTL computer

Very rarely do we see an Instructable so complete, and so informative, that it’s a paragon of tutorials that all Instructables should aspire to. [8 Bit Spaghetti]‘s How to Build an 8-bit computer is one of those tutorials.

[8 Bit Spaghetti]‘s build began on his blog. He originally planned to build a 4-bit computer but decided a computer that could only count to 15 would be too limiting. The build continued by programming an NVRAM as the ROM on a breadboard and finally testing his bundle of wires.

What really makes [8 Bit Spaghetti]‘s special is the Instructable – he covers just about all the background information like the definition of a Turing machine, a brief introduction to electronics and logic chips, and binary numbers. Even though he’s doing some fairly complicated work, [8 Bit Spaghetti]‘s tutorial makes everything very clear.

The computer isn’t quite done yet – there’s still a few nixie tubes to add – but we couldn’t imagine a better project for the budding electronic hacker.

8-bit computer project lands in a Philco radio case

We’ve enjoyed seeing the development progress of Veronica, [Quinn Dunki's] 8-bit computer project. It started out on a breadboard, then moved to edge-connected PCBs, and now [Quinn] has given Veronica a body of her own.

The donor is a Philco Model 42-327T and was produced in 1942. It was chosen because it is non-functional and missing several pieces. We wonder about the collector’s value of the piece but since [Quinn] snagged it from eBay there can’t be in huge demand right now. The teardown images are priceless. There seems to be no reasoning behind component placement for the beast. It looks more like a junk drawer packed full of relic components than something that actually worked once upon a time.

But we digress. After gutting the retro wooden case [Quinn] set out to fabricate her own face plate. Since she’s comfortable working with copper clad, she whipped up a negative design and etched the dashboard seen above. It mounts in the original dial opening, and hosts all of the controls she needs to work with the 8-bit computer. Just below is where the present buttons used to be located. You can just see the hexout display for reading data from the registers mounted in that void.

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