Browse Prior Art Database

Elimination of the Necessity of DRAM Testing at Initial Program Load

IP.com Disclosure Number: IPCOM000104906D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Blackmon, HL: AUTHOR [+6]

Abstract

A method of using a combination of Main Store availability functions to eliminate the need for power on or initial program load (IPL) main store diagnostics is disclosed. This enables the use of Continuously Powered Main Store without the destruction of data in Main Store due to testing patterns.

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This is the abbreviated version, containing approximately 53% of the total text.

Elimination of the Necessity of DRAM Testing at Initial Program Load

      A method of using a combination of Main Store availability
functions to eliminate the need for power on or initial program load
(IPL) main store diagnostics is disclosed.  This enables the use of
Continuously Powered Main Store without the destruction of data in
Main Store due to testing patterns.

      The elimination of main store diagnostics at IPL time is
implemented by making the reliability of the card such that it
doesn't fail during the normal system life.

      This method is the following:

o   On card Non-Volatile Storage Area

    -   This area is used to store failure information.  Because it
        moves with the DRAMs and is non-volatile, it gives a

        continuous record from build to end of life.  This enables
        the redundant bit steering registers to be loaded with the
        correct data immediately after power-up, without having to
        re-detect the failing modules.

o   Double Bit Correct ECC

    -   By using a true double-bit correct scheme on the ECC word
        that doesn't slow down the system, the probability of an
        uncorrectable error is greatly reduced.  In combination with
        this is the capability of using Redundant Bit Steering (RBS).

o   Redundant Bit Steering

    -   RBS gives the card the capability of replacing a failing
        module, during system operation, with a spare that is wired
        on the card.  This essentially increases the error correction
        capabilities to three bits.

o   Scrubbing

    -   RBS by itself is not very useful unless there is a way to
        determine which modules need to be steered out (replaced).
        By utilizin...