A Small Coincident-Current Magnetic Memory

This paper describes a small coincident-current memory used for buffer storage. Such a memory as part of the self-checking card-to-magnetic-tape converter, an auxiliary of the Univac System, is now in production. Typical advantages of a small coincident-current memory in computer input-output equipment, as well as some of the problems encountered in its application, are described. This memory affords the card-to-tape converter a great degree of flexibility, making it possible to read cards sidewise and to check and edit information with a minimum of hardware and complexity. Memory cells consist of metallic-tape cores wound with multi-turn coils. The low currents required permit operation of the memory directly from the card-sensing brushes on writing and from a diode function-table on reading. The functional aspects of the memory and its associated electrical circuitry are described. Information concerning the physical nature of the memory, specifications of the cores, and some of the tests performed in their inspection is also presented.