Browse Prior Art Database

Programmable Storage Card Select Shifter

IP.com Disclosure Number: IPCOM000038324D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Malmquist, CA: AUTHOR

Abstract

A system which uses hard wired storage cards, which are selected by control logic, could not function if the first card was inoperable and its memory space was required for vital data to initial program load the system. The installation of an additional register, which holds the value of the number of positions to rotate the card select lines, allows the system to function in the event of a card failure. The register is scannable so that it can be changed at any time that a card is determined to be defective.

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Programmable Storage Card Select Shifter

A system which uses hard wired storage cards, which are selected by control logic, could not function if the first card was inoperable and its memory space was required for vital data to initial program load the system. The installation of an additional register, which holds the value of the number of positions to rotate the card select lines, allows the system to function in the event of a card failure. The register is scannable so that it can be changed at any time that a card is determined to be defective. If the system has seven cards and the first card is defective, the shift amount register is set to one, causing: Storage Card #2 to have Card Select #1 Storage Card #3 to have Card Select #2

Storage Card #4 to have Card Select #3

Storage Card #1 to have Card Select #4 The value in the maximum storage size register would be reduced in value to the storage size of the defective card. This eliminates the defective card from the system. Any card found to be defective can be eliminated by this process by shifting the select lines so that the defective card would be the last card selected. This scheme also works for any multiple set of failing cards which were adjacent to one another, i.e., if cards 2 and 3 are defective the select lines are shifted three positions so that: Storage Card #4 has Card Select #1 Storage Card #1 has Card Select #2

Storage Card #2 has Card Select #3

Storage Card #3 has Card Select #4 The memory s...