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Combined Transfer Latch Secondary Selector in an Associative Store

IP.com Disclosure Number: IPCOM000073524D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Hardwick, IR: AUTHOR [+2]

Abstract

Each word location of an associative store has at least one selector trigger which is set to select the word for accessing. Frequently the `Next' is defined for the store, which involves connecting the selector triggers as a shift register with the usual transfer latch between each successive pair of selector triggers, and calls for a shift in the states of the selector triggers in a given direction.

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Combined Transfer Latch Secondary Selector in an Associative Store

Each word location of an associative store has at least one selector trigger which is set to select the word for accessing. Frequently the `Next' is defined for the store, which involves connecting the selector triggers as a shift register with the usual transfer latch between each successive pair of selector triggers, and calls for a shift in the states of the selector triggers in a given direction.

In the associative store shown, each word location 11 has two selector triggers, a primary 12 and a secondary 13, either or both of which can be chosen to distinguish the word locations to be accessed. The Next operation is defined only on the primary triggers 12, the secondary triggers 13 being used as transfer latches. The secondary triggers must be reset before being used as transfer latches and their states are, therefore, lost when the Next operation is performed. The logical circuitry for each word location includes AND gates 14 and 15, the outputs of which are ORed by the gate 16 onto a word line. By selecting the appropriate Key inputs P and S to the gates 14 and 15, it is possible to read out the state of the primary trigger, the secondary trigger or the OR function of the states of both triggers.

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