Marble Madness

What exactly is a computer? Today most of us automatically think of a digital computer, and probably with a von Neumann architecture. But that was not always the case. The early history of computing was filled with a wild assortment of machines and concepts. From Charles Babbage’s mechanical Analytical Engine to the electromechanical Mark I, the field was rich with varied approaches. Other early computers included the room-sized ENIAC, which utilized vacuum tubes, as well as analog computers used for scientific calculations and military applications.

While at the recent EMF Festival, YouTuber and hardware hacker Sam Battle (AKA Look Mum No Computer) came across a very intriguing display. It was an art installation called the Supercomputer that is made up of wood, marbles, tubing, plastic rails, and metal gates that actually perform simple computations, despite the fact that the Supercomputer looks nothing like a modern computer. However, the Supercomputer was completely disassembled and in piles so that EMF Festival attendees could experiment with it or even rebuild it.

But no one did. Still, Battle was intrigued by the device and wanted to understand how it worked, so after the festival wrapped up, he picked it up and carted it off for reassembly. Fortunately, there was a fair amount of documentation explaining how components of the Supercomputer work, like the various marble-powered logic gates. This documentation was by no means a step-by-step assembly guide, however, so Battle still had a lot of reverse engineering to do.

As the build progressed, it soon became clear that things were just not going to fit together as expected. Luckily, Battle was able to meet with the artist that created the device, Jem Finer, to help answer some questions about the mysteries of the Supercomputer. As it turns out, the device was created to run a cellular automata algorithm — something like Conway's Game of Life.

Finer went into the set of eight computational units that carry out this algorithm and how they interact with one another. With a wealth of tips and some pictures of the original installation, Battle was ready to get back to work. Unfortunately two of the computational units were damaged, but the Supercomputer was still painstakingly reassembled with the six surviving units.

The end result is not only a mesmerizing piece of art, but it is also a functional (if very odd) computer. Data flows through the system in the form of marbles. These marbles interact with the computational units before arriving at the five-bit output unit (where they are accompanied by a note played by a xylophone bar for good measure), which determines whether each simulated cell survived the past cycle. Surviving marbles are then lifted back up to the top of the machine where they are dropped in as inputs for the next round.

Battle still has some work to do to completely finish the rebuild, but promises a new video (perhaps with a few musical enhancements!) is on the way soon, so stay tuned.