Electronic Design

Magnetic Computer Uses Multiaperture Cores

An airborne, guidance-type computer that would use magnetic circuitry for logic as well as for memory is being built by Sperry Gyroscope Co., Great Neck, N.Y. Basic clock rate of the system is to be 600 kc sine wave, which is said to make possible more than 12,000 additions or subtractions of 24-bit single words per second.

Except for a sense amplifier to sense memory output, and a control-pulse generator for synchronization, both of which use semiconductors, all logic, registering, gating, and memory functions are implemented with magnetic elements, according to Sperry. These elements are mainly single-hole and two-hole multiaperture cores and permalloy cores of special design, the company says.

The computer is being built for the Air Force's Aeronautical Systems Division at Wright Field, Ohio. The Air Force is reported to be supporting the project in the hopes of achieving a highly-reliable computer through all-magnetic design. A feasibility model is scheduled for delivery to Wright Field in April, 1962.

Performance goals include: operation for up to 20,000 hours without maintenance; operation at temperatures from 55° to 125°C; a weight of 19 lb; a volume of 0.5 ft3; a power consumption of less than 90 W; and high resistance to nuclear radiation. The main memory would contain 400 17-bit words in two-hole cores; a data memory would store 256 24-bit words.

The system uses four-pulse, dynamic logic. Company engineers report they are designing similar circuitry to work at more than 1 mc. One magnetic circuit is said to have operated at around 5 mc. (Electronic Design, Oct. 11, 1961, p. 27)

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