Browse Prior Art Database

System Correction of Alpha Particle Induced Uncorrectable Error Conditions by a Service Processor

IP.com Disclosure Number: IPCOM000051619D
Original Publication Date: 1981-Feb-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Sager, GS: AUTHOR [+2]

Abstract

This scheme has a computer system verify that an alpha particle error exists and correct it.

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System Correction of Alpha Particle Induced Uncorrectable Error Conditions by a Service Processor

This scheme has a computer system verify that an alpha particle error exists and correct it.

A central processor (CP) 10 fetches data. The data from storage 12 is protected by error correction code (ECC) to detect and correct single-bit errors and to detect double-bit errors. Normally when a double-bit error is detected by such a code, it means an uncorrectable error (UE) condition exists.

The steps are described below for CP correction of certain UEs.

1) The central processor 10 stops when storage 12 signals a UE is detected in a data word. The service processor 14 normally will bring the control processor back to a retriable point to retry the fetch.

2) After the control processor 10 is restored where it can run its microcode and its cache purged, the following takes place: a) The service processor 14 fetches the failing storage line and cross-interrogates to get the address assigned to the service processor. b) The service processor 14 issues a diagnostic fetch command to fetch the failing data word and save it. This diagnostic fetch inhibits any detection of a UE from storage 12 and no cross- interrogation takes place. c) Service processor 14 issues read syndrome to fetch the syndrome bits from the system controller 16. d) Service processor 14 verifies that the syndrome bits do not indicate that this may be a forced UE word. If it is, there is no attempt at correction. e) Service processor 14 does a diagnostic store and fetch of diagnostic patterns to the data word. f) Service processor 14 analyzes data obta...