A Tangible Computer for Science Museums: Pilot Machine

<div> A fully tangible computer using marbles for information storage could be a convenient demonstrator for museums devoted to computer science. We present the architecture of a binary stored-program machine, the key technologies we use for memory, processing and control units. After a review of related work, we discuss the results of a pilot study conducted with a restricted system. The pilot machine has 10 memory registers for 8-bit words, two physical operators and an electronic control unit. Its instruction set allows iterative programs such as x = 240; while (x is even) x = mix(x);. Public presentations have been conducted successfully but suggested some modifications that we report. Our forecasted final machine will feature a tangible control unit, 64 12-bit registers, and 16 instructions. It will occupy approx. 25 m 2 in a dedicated room at the Palais de la découverte in Paris. </div>