Called the Entabulator, it can read punch cards

Sep 27, 2014 09:26 GMT  ·  By

Have you ever heard of a completely mechanical computer? If you haven't, you might want to know that they existed and sold prior to the 1990s, especially in the sixties and seventies. For example, one that sold in 1960 could calculate square roots.

Mechanical computers are made from levers, gears and various other physical components. Adding machines and mechanical counters are the most common types.

Now, though, an electrical engineer from New York City, Chris Fenton by name, has created one that can read punch cards.

Don't let his profession fool you. He really did make a fully mechanical computer, one that uses no electricity. Admittedly, he did try with electricity first, making the 3D-printed FIBIAC.

The Turbo Entabulator

The new machine doesn't use electricity at all but can still perform around one micro operation per second. He calls the new machine the Turbo Entabulator. It employs spring-loaded pins and punch-cards to read an instruction stream rather than an infrared card-reader.

Sure, he went through 20 prototypes, but he managed it in the end. The contraption has three single-digit base-ten registers and a ten-hook Jacquard-style punch card reader. Two hooks assigned to each counter add or subtract from the register (don't select both, because the machine will jam and snap), while a reading of “zero” will cause spring-loaded lever attached to each counter to raise.

Also, when a zero-detect lever gets read, a shaft that runs the length of the machine lifts a “catch” mechanism to rotate the “cylinder” of the punch card reader advancing to the next instruction.

A pretty complicated project, all told, but that was the whole point, to test the limits of his inventiveness. A MakerBot Thing-o-Matic 3D Printer was used to produce all the parts (except some nuts and bolts, springs, rubber bands, and tiny bearings).

The design

As you can see in the attached photo, and the video embedded below, the Entabulator isn't all that large, taking up the same space as a food tray at most. Granted, it isn't all that fast either, but there was never any chance of the thing doing anything even close to a real computer.

Chris Fenton must have had a lot of patience. He also must possess a high degree of selflessness, or a really good sense of humor, because he has uploaded the plans for the contraption on Thingiverse. Go ahead and check them out if you want to build something similar. Might make for a good science project.