Today’s world runs on digital computers, but there was a time when people relied on their analog siblings. Instead of electrical signals, mechanical computers utilize complex systems of gears, weights, and other physical implements to perform tasks. As recently as the 1960s, accounting devices like the Soviet Union’s Ascota 170 could even perform square roots, but some of the earliest mechanical computers may even trace all the way back to the famous Antikythera mechanism. Discovered in an ancient shipwreck near Crete in 1901, experts now believe ancient Greeks built the device around 100 BCE to calculate astronomical positions.

Mechanical computers may not oversee today’s automated tasks, but it’s still possible to build your own using literal children’s toys. That said, one YouTuber’s ongoing DIY mechanical computer project looks so dizzyingly complex that—for the time being—most people will likely stick with their smartphone’s calculator app.

The inventor who goes by Shadowman39 on YouTube is a longtime Knex aficionado. His previous projects built from the connectible, plastic building pieces include everything from coin sorters, to gigantic motion machines, to even a functioning Skee Ball cabinet. More recently, he opted to design and construct a device capable of performing basic calculations like addition and subtraction. Although he’s planning on expanding its abilities, the YouTuber recently uploaded the first look at his Knex 8-bit mechanical computer—specifically its “very simple” arithmetic logic unit, or ALU.

“Very simple,” in this case, refers to a roughly 3.5-foot-tall contraption built using thousands of Knex pieces, wheels, and conveyor belts. All those parts are divided up into eight columns, each one responsible for a single bit of binary data represented as a 0 or 1. The 8-bit system is capable of handling operations using the numbers 0-255, although Shadowman39 notes (using some rather dense mathematical reasoning) that it can also work with the number range of -128 to 127.

While there is an electrical line to power initial movement, the actual calculations themselves take place through mechanical means. Depending on the user’s input, the Knex computer will use its rack and pinions to initiate cranks capable of rotating 360 degrees while anchored by a pair of weights and counterweights. These actions compound across the eight columns until a calculation is completed.

“It looks like a mess but I promise it’s just organized chaos,” the inventor says at one point.

You might just need to take his word for it on that front. In any case, the YouTuber promises additional videos are coming that will delve into how data and program storage will work in its RAM and ROM. It may not find its way onto desktops, but the Knex project highlights the uniquely tactile and ingenious designs required to construct even the most rudimentary of mechanical computers.

 

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