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Memory Addressing Circuitry

IP.com Disclosure Number: IPCOM000098051D
Original Publication Date: 1961-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Smith, JL: AUTHOR [+2]

Abstract

With cryotrons, higher switching speeds are obtained if (1) the number of circuits which any one circuit drives is limited and (2) if the number of circuits which drive any one circuit is limited. Stated differently, higher speeds are obtained if fan out and fan in of the circuitry is limited. In memory systems, the limitation on fan out necessitates the use of multistage addressing circuitry on the memory input. The limitation on fan in necessitates the use of multistage converging circuitry on the memory output.

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Memory Addressing Circuitry

With cryotrons, higher switching speeds are obtained if (1) the number of circuits which any one circuit drives is limited and (2) if the number of circuits which drive any one circuit is limited. Stated differently, higher speeds are obtained if fan out and fan in of the circuitry is limited. In memory systems, the limitation on fan out necessitates the use of multistage addressing circuitry on the memory input. The limitation on fan in necessitates the use of multistage converging circuitry on the memory output.

Each bit position of the memory (top drawing) is addressed by a four bit address A, B, C and D for reading and by a four bit address E, F, G and H for readout. There are three major sections: addressing circuitry 21, the memory itself 22, and output addressing circuitry 23. Memory 22 has sixteen bit positions, each having two inputs and an output. Simultaneous activation of the two inputs to any bit position is needed in order to store a 1. Whether a 1 or 0 is to be stored in any particular bit position is indicated on bit input 16. The particular position where it is to be stored is indicated by the four bit address A, B, C and D.

The outputs of those bit positions storing 1's are continuously active. Output circuit 23 selects, with address digits E, F, G and H, a particular one of the outputs and gates this to final output line 26.

An example of how each of the eight selector switches 41...48 are fabricated with cryotronic...