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Memory with Error Correction under Repair Mode Operations

IP.com Disclosure Number: IPCOM000090777D
Original Publication Date: 1969-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Lee, HT: AUTHOR

Abstract

A word-organized memory with removable bit planes and capability for Double-Error Detection/Single-Error Correction DED/SEC is adapted to continue operating while a bit plane card containing a faulty bit storage component is removed for component repairs. Such repair mode operation is achieved by mounting service card 1 in the memory bit plane position X vacated by the card undergoing repair.

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Memory with Error Correction under Repair Mode Operations

A word-organized memory with removable bit planes and capability for Double-Error Detection/Single-Error Correction DED/SEC is adapted to continue operating while a bit plane card containing a faulty bit storage component is removed for component repairs. Such repair mode operation is achieved by mounting service card 1 in the memory bit plane position X vacated by the card undergoing repair.

Card 1 contains flip-flop 2 with output 3 adapted for connection through memory output channel 3a to the Xth bit stage of memory output buffer 4. The complementing input 5 of flip-flop 2 is coupled through single-shot 6 to DED output indicating line 7 of the error-detection and correction circuits 8. Thus, the state of flip-flop 2 is reversed for a retrial when and only when a double error is detected by circuits 8.

Assuming that flip-flop 2 is in an arbitrary 1 or 0 state when a memory cycle is taken, the table summarizes the error state possibilities at cycle completion, the retry operation if any, as indicated by the arrow heads, and the ensuing results in this memory system. In the table, p(e) the probability of making an erroneous single error correction E-SEC when there are actually three errors in a code word, e.g., in the case of a 72,64 SEC/DED code, p = 72/127 = 0.566. Also included in the table for comparison are the results with the conventional system in which no provision for retrial is made.

The followi...