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Operating Position Tree Circuit

IP.com Disclosure Number: IPCOM000092566D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Lindquist, AB: AUTHOR

Abstract

Some associative memories have a sort register, a mask register and an interrogate register. Outputs of these registers are represented by S, M and I with subscripts 1...n that signify particular register positions. Letters without subscripts are used where the description applies to each of these outputs. These outputs define an operating position. The operating position is the right most position where SM=1. A 1 in a bit position of the sort register is assumed to indicate sorting on that position and a 1 in a bit position of the mask register indicates masking on that position. For each register position there is an Or-Invert O-I 2 that produces an output F when the associated position is the operating position. Each O-I 2 receives sort and mask inputs for the associated position.

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Operating Position Tree Circuit

Some associative memories have a sort register, a mask register and an interrogate register. Outputs of these registers are represented by S, M and I with subscripts 1...n that signify particular register positions. Letters without subscripts are used where the description applies to each of these outputs. These outputs define an operating position. The operating position is the right most position where SM=1. A 1 in a bit position of the sort register is assumed to indicate sorting on that position and a 1 in a bit position of the mask register indicates masking on that position.

For each register position there is an Or-Invert O-I 2 that produces an output F when the associated position is the operating position. Each O-I 2 receives sort and mask inputs for the associated position. Each O-I 2 except the right most circuit also receives an input C that tells whether any register position to the right satisfies the condition SM=1. For the general case, C(i-1)= S(i)M(i)I(i)C(i). The subscript i represents any value between 2 and n. The term S(i)M(i) tells whether the associated position might be the operating position. The term I(i) tells whether the sort process is to continue beyond the associated position. The term C(i) tells whether any position to the right is the operating position.

For each register position there is a circuit 3 that receives the sort, mask and interrogate inputs and produces an output A=SMI. Other circuits combine these outputs and form the C signals. A feature of this operating position circuit is that it uses a tree configuration that speeds up the formation of these signals.

Logic block 4 illustrates the operation of the tree. Block 4 r...