Browse Prior Art Database

CRC Write Verification

IP.com Disclosure Number: IPCOM000106287D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Christianson, MD: AUTHOR [+4]

Abstract

A technique for detecting the failure of 8-bit memory modules and subsequently regenrating lost data during error recovery is described. The technique includes the use of address boundaries which are not aligned on 'powers of two' values, horizontal parity across corresponding bits of each memory module, vertically generated CRC, and automatic read-back of written CRC values.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

CRC Write Verification

      A technique for detecting the failure of 8-bit memory modules
and subsequently regenrating lost data during error recovery is
described.  The technique includes the use of address boundaries
which are not aligned on 'powers of two' values, horizontal parity
across corresponding bits of each memory module, vertically generated
CRC, and automatic read-back of written CRC values.

      When using nonvolatile solid state 8-bit memory modules, error
detection and recovery is a concern due to the lack of a 9th bit for
parity checking on each individual byte of data.  In a situation
where the memory is being used as a write cache, the ability to
regenerate data if a module failure occurs is of the utmost
importance.

      Data is intentionally not aligned on boundaries which have
addresses that are of a power of two.  This helps to ensure that any
stuck address lines to the memory modules will not result in
undetected data corruption.  Stuck address lines can be detected
during a memory test which uses data packets of the specified
size(s).  By writing different data patterns to each packet of data,
the test can virtually ensure that no stuck address lines exist.

      Horizontal parity across corresponding bits of the memory
modules helps to ensure data integrity and is used to reconstruct
data which might otherwise be lost when a module failure occurs.  If
four 8-bit memory modules are used to form a 32-bit data word, a
fifth 8-bit mo...