The magnetic-drum store of the computer Pegasus

The paper describes the mechanical detail, logical arrangement and electronic design of a fully-packaged drum storage system. The mechanical design of the drum has been based on current extremeprecision machine-tool practice, for reliability. Methods of track selection are electronic on both writing and reading, taking the form of electronic cross-bar switches. On the reading side, the switch is formed by an array of balanced germanium-diode gates which are interposed directly after the magnetic heads, prior to amplification. The system reliability proved to be very satisfactory in the light of the first 1500 hours´ operating experience.