The IBM 705 EDPM Memory System

The IBM 705 memory system utilizes magnetic cores both as a storage element and also in a matrix address selection system. The magnetic core has been established as a memory element for large data processing machines. The core compares very favorably with other means of storage with respect to such factors as speed, reliability, size, cost, life, and simplicity of associated electronic circuitry. The memory consists of a main 20,000 character unit and a 512 character storage unit. Both are three-dimension coincident current systems with the larger containing 35 planes of 4000 cores each and the other consisting of seven planes of 512 cores each. The basic memory cycle is 9 ¿s long when operating with the input-output units or on internal transfer of data. When operating with the central processing unit a 17-¿s cycle is required. Data may be transferred within memory in five character blocks, and the five character instructions are transmitted to the control unit in one-memory cycle. Transfers between memory and the input-output and arithmetic units is serial by character. Use of the magnetic core matrix switch greatly reduces the electronic equipment required to drive the memory. Simplified circuitry requiring no adjustments eliminates any maintenance time required for making routine adjustments. Indefinite life of the core eliminates any replacement problem of the basic storage element itself.