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Word Checking and Correcting Unit

IP.com Disclosure Number: IPCOM000097752D
Original Publication Date: 1961-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Bahnsen, RJ: AUTHOR [+3]

Abstract

This checking unit may be used in large computers to detect and, where possible, to correct errors in data or instruction words transmitted between sections of the machine. Generally, a word in memory should have an error correcting code ECC attached to it, but the same word in an operating section should contain a parity bit for each byte having a unitary use. As the bytes used will not be the same in all sections, the parity bits or the ECC should be changed as a word is transferred between sections.

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Word Checking and Correcting Unit

This checking unit may be used in large computers to detect and, where possible, to correct errors in data or instruction words transmitted between sections of the machine. Generally, a word in memory should have an error correcting code ECC attached to it, but the same word in an operating section should contain a parity bit for each byte having a unitary use. As the bytes used will not be the same in all sections, the parity bits or the ECC should be changed as a word is transferred between sections.

A data word is received on bus 1 and is applied to ECC generator 2 and to parity bit generators 3 and 4. These generators are shown separately but may conveniently be in one unit with separated output busses to receive the appropriate parity and ECC bits. The incoming word will usually have check bits associated with it and, depending on the origin of the word, these check bits are gated by gates 5, 6 or 7 from the in busses into comparing units 8, 9 or 10. These also receive the generated check bits from the corresponding generators 2, 3 and 4. Any discrepancy between the received and the generated check bits causes an error signal to be sent to an instruction control by the comparator to start a correction routine.

When the word received is from memory and includes ECC bits, the ECC compare unit 8 also determines if a detected error is correctable. If so, it activates an error decoding unit 11 which controls a data corrector 12 t...