A Twitter Connected Mechanical Calculator

The TwitALU

Two students at the University of Bristol wanted to create a computer to demonstrate how ALUs work. The result is the TwitALU, a Twitter connected mechanical calculator.

The device uses a custom 7400 series ALU based on the famous MOS 6502 processor. Instead of doing the calculations on a silicon die, the ALU drives mechanical relays. This produces a nice clicky-clacky sound as the calculation is computed.

To start a calculation, you tweet @twittithmetic with your input. A Raspberry Pi is used to load the instructions into the ALU. Once the computation is done, it’s tweeted back to you and displayed on the Nixie tube display. It’s not efficient, or fast, but it does the job of demonstrating the inner workings of the device while doing simple math.

The device’s schematics are all available on the website, and are helpful for understanding how a simple ALU works. After the break, check out a quick clip of the TwitALU in action.

11 thoughts on “A Twitter Connected Mechanical Calculator

  1. Wow, I almost forgot about how twitter once was, nice and fringe instead of a political/media/facebook type of thing, where your expressed views must be mainstream or you are arrested.

    Sigh. It never ends well does it.

    1. It’s the first time in history there’s been a soapbox that people actually listen to. In real life street speakers are usually undermedicated schizophrenics, religious nuts, schizophrenic religious nuts, or trying to scam you.

      Now we have the Internet where that’s only 75% true.

      I’m pissed off at the ISPs killing Usenet off. Uncensorable and uncentralised by design, owned by nobody and everybody, and it worked fantastically on any cheap old hardware. I bet governments were happy to see it go. All that really needed doing was dropping binary groups / posts, but it was a big enough pain in the ISPs arses that they were glad for the excuse to let it go.

      Usenet’s the whole reason I got on the bloody Internet. There’s a few free servers out there, still. At the moment my Internet connection doesn’t seem to pass NNTP.

      1. Most usenet outfits allow alternative ports because of that port block trend though, although yes it can’t be the same as it was in the past even when you get it going.
        And IRC is still around I think, however I don’t know how diluted that got over time and how much control they pushed onto that. I imagine it could still be pretty OK though if you have a server to which you connect in the classical way and it doesn’t have some web interface for people to use.
        In fact after my post I was actually thinking of perhaps trying IRC out again.

    1. It isn’t mechanical either even if you’re just looking at the relay part. A mechanical calculator would be more like a Curta calculator. This is an electromechanical ALU bolted onto that 6502.

      Still, pretty nice build and lots of blinky lights which are always good :D

    2. More like an electronic calculator that is dependent on a mechanical element. Or, a calculator that could be way more efficient by eliminating the mechanical element. Still pretty cool.

  2. Stop sullying what’s actually good about projects by giving them sensationalist labels. No one who’s seen a mechanical calculator would ever call this project a mechanical calculator. It is cool, though.

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