The logic design for a mechanical computer conceived by Charles Babbage around 1834, but never built. The design envisioned a memory of a thousand 50-digit numbers. The machine, which could do addition, subtraction, multiplication, and division, was to be controlled by programs punched into loops of cards; the machine was thus to be directed through a variety of computations, and alternative paths could be taken depending on the values of intermediate results. It was to have included a printer to obtain the results. The design was remarkable in anticipating so many elements of modern computers.