Satire Inspires Peter Jansen to Build the World's First and Only Coin-Operated TI Calculator Cab

A satirical article poking fun a arcade collectors and software-as-a-service alike may seem like an odd inspiration for a hardware project, but self-described "open source mad scientist" Peter Jansen's coin-operated graphing calculator arcade cabinet proves it's possible.

"Local man Alton Yates was reportedly overjoyed Wednesday after scoring a vintage coin-operated Texas Instruments graphing cabinet," an article published last year on satirical outlet The Onion reads. "I can’t resist the nostalgia," the fictitious interview with the non-existent Yates continued, "as soon as I look at this thing, it brings me right back to being a teenager, meeting up after school to watch classmates plot the amplitude, period, and phase shift of a standard graph while we all cheered them on."

But what if, Jansen asked himself, it wasn't satire? The result is, Jansen says, "perhaps one of the strangest projects I've ever put together": A genuine, fully-operational Texas Instruments-branded coin-operated calculator cabinet, the only one of its kind in this world or any other.

"The article just really cracks me up, but possibly the best part is the picture — equal parts brilliant, beautiful, and offensive to the eyes in a way that only 70s/80s wood paneling could be," Jansen writes. "I felt strangely compelled to make one, and with my father coming to visit for the holidays, it gave us a perfect quick project to help keep us both out of trouble (and an excuse to teach my 4 year old how to sand...)"

Designed to mimic, as far as possible, the appearance of The Onion's mock-up, the plywood cabinet stands around five feet tall and is 14 inches deep. Controls are handled by a pair of rotary encoders at the front, driving an on-screen cursor for entering equations using a pop-up keyboard.

"Everything is off-the-shelf," Jansen writes of the hardware, "so there isn't much to it. A Raspberry Pi drives an ancient 4:3 LCD monitor I found on Craigslist. An Arduino Uno interfaces with the encoders, as well as the coin acceptor, and streams these as serial data to the Pi at 115200 baud. A quick graphing calculator program written in PyGame takes care of all the graphics and logic."

While functional, however, the cabinet doesn't make calculation cheap: At a quarter a plot, Jansen jokes, "you don't want to be in the terrible position of choosing between quarters for laundry and quarters for graphing."

The full write-up is available on Jansen's Hackaday.io project page.