Virtual DC II app for iPhone and iPad

A recreation of the original marble computer marketed in the 1960s by ESR.

A company named ESR made it possible for children to find a working digital computer on toy store shelves in the 1960s. The toy consisted of plastic parts, boards, and marbles, and required some assembly. Simply by having marbles roll down a board, follow paths, and bump into plastic parts it became possible to count in binary and do arithmetic. All while demonstrating basic computer concepts.

We’ve made some changes to the original design in bringing you this recreation. We’ve added convenience switches on the right, but you can still move flip-flops and switches manually. We’ve also added a set of lights on the play field to make it easier to visual the binary patterns (and to finally satisfy all those children of the 60’s when they found there were no batteries or wires inside their new marble computer). Additionally, there is an automatic ball return and some sound effects upon overflow of the M/Q and Accumulator registers, or when a stall occurs. We sincerely thank the designers of the original Digi-Comp II and ESR for bringing the original product to market. The original undoubtedly launched many into their computer careers.

Please realize that you’re not going to be crunching huge numbers. The maximum values for each register is as follows:

M/Q 7
M 16
Acc 127

This is not an action-packed video game. Rather, it demonstrates basic computer concepts. Take a moment to reflect and admire the genius of the original designers. With this app, we pay homage to the original designers and ESR for bringing the original device so many of us children of the 60s.