The HEC computer

The HEC4E computing machine was designed specifically for application to commercial calculations. It is an electronic digital machine of medium size functioning in the serial binary mode, the pulse repetition frequency being 40 kc/s and the word length 40 binary digits. The main storage for both numbers and instructions is a magnetic drum having 64 tracks each holding 16 words. Besides being able to perform all four arithmetic functions automatically, the machine has facilities for the automatic conversion to and from the binary scale for any normally used scale of notation. The input is by means of standard punched cards, and both a printing mechanism and a card punch are provided for the output of results. The machine is constructed in four physical units: the elec tronic unit, containing approximately 1100 thermionic valves; the operating console, providing manual controls and a visual display of the course of calculation; the tabulator providing both punched card input facilities and the printed output; and the card-punching output mechanism.