The Binac

Abstract

The Binac was the first high-speed electronic digital computer of its type to be completed. It consists of a main computing section, input-output equipment, and a mercury delay-line memory of 512-word capacity. Although designed for a specific purpose, the Binac is well adapted to any type of general mathematical computation. While the number of tubes is comparatively large, the Binac is a combination of a few basic circuits. Extensive use is made of crystal diodes in switching or gating circuits. These circuits fall into three basic classifications: function tables or diode matrices, used for converting coded groups of signals such as instructions into corresponding but differently coded groups of signals to operate switching circuits; switching gates, which control the flow of information in accordance with signals received from function tables or similar sources; and reshaping gates, which, as their name implies, reshape signals that have become distorted in electric delay lines or other circuits. The use of reshaping gates, together with suitable shaping networks, makes possible the use of a "pulse envelope" or "non-return-to-zero" system of representing information, thus effectively doubling the bandwidth of circuits. Crystal gates are used with electric delay lines to form a serial binary adder. A one-word register is formed by combining an electric delay line with appropriate reshaping gates, input and output gates, and amplifiers, all connected to form a closed loop. Insertion of the adder in the loop results in an accumulator.