Retrotechtacular: A Mechanical UART

We’ve heard it said that no one invented the old mechanical Teletype. One fell from the sky near Skokie, Illinois and people just duplicated them. It is true these old machines were similar to a modern terminal. They sent and received serial data using a printer instead of a screen. But inside, they were mechanical Rube Goldbergs, not full of the electronic circuits you’d think of today.

Teletype was the best-known name, but there were other mechanical monster terminals out there. [Carsten] recently took some pictures of his 99 pound Olivetti mechanical terminal. According to him, there’s only one electronic component within: a bistable solenoid that reads the data. Everything else is mechanical and driven with a motor that keeps everything at the right baud rate (110 baud).

Like the Teletype, it is a miracle these things were able to work as well as they did. Lacking a microcontroller, the terminals could respond to an identity request by spinning a little wheel that had teeth removed to indicate which letters to send (TeleType used a similar scheme). Things that are simple using today’s electronics (like preventing two keys pressed at once from being a problem) turned out to be massive design challenges for these old metal monsters.

Turns out that when [Carsten] last fired the terminal up, a capacitor finally gave up its magic smoke. He plans to fix it, though, and as long as it isn’t a mechanical problem, we bet he will.

We’ve talked about Teletypes a few times in the past, including using them for text messaging and even Twitter.

Relays Calculate Square Roots

After seeing an exhibit of an old relay-based computer as a kid, [Simon] was inspired to build a simple two-relay latching circuit. Since then, he’s been fascinated by how relays can function to do computation. He’s come quite a long way from that first latching circuit, however, and recently finished a huge five-year project which uses electromechanical relays to calculate square roots.


The frame of the square root calculator can hold up to 30 identical relay modules, each of which hold 16 relays on PCBs, for a total of 480 relays. The module-based setup makes repair and maintenance a breeze. Numbers are entered into the computer by a rotary dial from an old phone and stored in the calculator’s relay memory. A nixie tube display completes the bygone era-theme of the device and shows either the current number that’s being entered, or the square root of that number as it’s being calculated.

The real magic of this project is that each relay has an LED which illuminates whenever the relay is energized, which shows the user exactly where all of the bits of the machine are going. [Simon] worked on this project from 2009 and recently completed it in 2014, and it has been featured at the San Mateo Maker Faire and at Microsoft Research in Redmond, WA. We’ve seen smaller versions of this before, but never on this scale and never for one specific operation like square roots.

Video below. Thanks to [Bonsaichop] for the tip!

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3D printed hand-cranked digital computer

What a beautiful thing it is to see this digital computer in action. [Chris Fenton] did an amazing job of designing and printing this mechanical digital computer. If you’re interested in one to call your own check out the source files he published this week.

[Chris’] design inspiration came from some research into Victorian Era mechanical looms. He adjusted the concept to build a punch card reader, starting with a capacity of three holes and moving to this design which can read ten holes. It provides just enough bits to address all three of the counters pictured above. Program the computer by inserting a punch card that is the size of a business card and crank away. The video below shows the process from afar… hopefully he’ll post a follow-up video with closer views of each piece in action.

This isn’t his first basic computing machine. Check out the electromechanical version from last year.

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Mechanical Donkey Kong features laser cut Mario

[Martin] just sent in a project he’s been working on that takes Donkey Kong out of the realm of pixels and sprites and puts our hero Mario into a world made of laser cut plywood.

This mechanical version of Donkey Kong uses an Arduino stuffed into an old NES to control Mario jumping over ball bearing ‘barrels.’ The game starts with 12 of these barrels ready to be thrown by our favorite gorilla antagonist, which Mario carefully dodges with the help of a pair of servos.

This is only the first iteration of [Martin]’s mechanical version of Donkey Kong. The next version will keep the clever means of notifying the player if Mario is crushed by a barrel – a simple magnet glued to the back of the Mario piece – and will be shown at the UK Maker Faire next year.

Although [Martin]’s ideas for a mechanical version of Donkey Kong aren’t fully realized with this build, it’s already a build equal to electromechanical Pong.

A 3D printed, electromechanical computer

If you had a machine that could print complex mechanical parts in an hour or so, what would you do? [Chris] is doing the coolest thing we can imagine and is building an electromechanical computer from 3D printed parts.

You may remember [Chris] from his efforts to getting his tiny, 1/10th scale Cray-1 supercomputer up and running. Even though he has the OS on a disk, actually booting the machine is a bit of a problem; much the same as his electromechanical computer project. Late last year we saw [Chris] building a few gears for his computer, but now he’s got a punch card reader that looks very much like a Jacquard loom.

Even though the computer doesn’t actually do anything yet, it’s amazing to think that [Chris] is building out of plastic that will run computer programs. You can check out the video of [Chris]’ video of his punch card reader after the break.

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Antique Electromechanical Calculating Machines

electromechanical calculator Hamann 505

The decision to use electronics for our calculating machines has long been decided.  However, that doesn’t mean that mechanical engineers didn’t put up a valiant, if ultimately futile, fight. [] has an interesting article comparing the calculating technology of the 1960s, such as the [Haman 505], to today’s iPad.

This comparison and pictures were made possible by [Mark Glusker]’s excellent collection.  These models can be divided into two categories, rotary calculators, and printing calculators. According to [Mark]‘s site, the printing calculators stayed on the market a few years after the rotary calculators, which were off the market by 1970.

Although we may never see machines like these made again, anyone even a little bit mechanically inclined would be hard pressed not to be inspired by this collection. Be sure to check out the video of a [Madas 20BTG] calculator after the break to see what one of the rotary models looks like in action! Continue reading “Antique Electromechanical Calculating Machines”

3D printed electromechanical computer

A few nights ago, [Chris Fenton] was hanging out at NYC Resistor putting in some time on his electromechanical computer project. You might remember [Chris] from his tiny Cray that he’s putting an OS on. It seems [Chris] is going back in time about 150 years and has set his sights on a 3D printed version of [Babbage]’s Analytical Engine.

The Analytical Engine was is a remarkable feat of engineering and machining. It was the first programmable computer. Shame, then, that it was never built in the 1800s. [Chris] isn’t building a glorified calculator like [Babbage]’s polynomial-computing Difference Engine – he’s going all out and building something with conditional looping.

[Chris] calls his device an electromechanical computer, so we’re assuming it won’t be crank driven like the version in the British Science Museum. Right now, he’s constructed the decade-counting gears that are vitally important for the ALU of his design. All the parts were printed on a Thingomatic, so we’re betting [Chris] is going to be relying heavily on the MakerBot automated build platform for the thousands of parts he’ll have to fabricate.

Check out the video from NYC Resistor after the break.
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