Browse Prior Art Database

Storage Verification Method

IP.com Disclosure Number: IPCOM000051151D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gerberich, CL: AUTHOR [+2]

Abstract

This article describes a method for optimally verifying main storage by finding all uncorrectable (double-bit) errors (UEs) in all possible combinations of data and error correction code (ECC) bits.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 73% of the total text.

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Storage Verification Method

This article describes a method for optimally verifying main storage by finding all uncorrectable (double-bit) errors (UEs) in all possible combinations of data and error correction code (ECC) bits.

The verification is done by programs executing on a processor having access to the storage being verified. The problem is to find UEs, including UEs that may result from errors in the ECC bits themselves, using a minimal set of bit patterns to test for all combinations of double-bit errors. First, the storage is tested with a pattern of all 0Os. A map is then made of all the single-bit ("stuck at 1") faults in storage. Then, another pass is made using a pattern of all 1's. This will catch all single-bit - "stuck at 0" -faults. The addresses of the "stuck at 0" faults are matched against the addresses of the "stuck at 1" faults to provide a complete double-bit error map. This method does not work in practice though, because of the number of expected single-bit errors. The time required to map all single-bit errors in a large storage makes this method unfeasible.

This article describes a minimal set of patterns for groups of 64 data bits (14 patterns) and then describes two additional patterns needed to completely cover the related eight ECC bits as well. These 16 patterns provide total coverage of all double-bit errors which may occur in any 72-bit group tested by the 16 patterns.

The patterns, represented in hexadecimal, are as follows:

1....