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Test Block Dynamic Test of Storage Protect Correctable Errors

IP.com Disclosure Number: IPCOM000120950D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Christensen, NT: AUTHOR [+5]

Abstract

The storage key in some designs has the data portion protected by a parity bit. Other designs can use an error correcting code that will allow correction of single bit errors, detection of double bit errors.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 95% of the total text.

Test Block Dynamic Test of Storage Protect Correctable Errors

      The storage key in some designs has the data portion protected
by a parity bit.  Other designs can use an error correcting code that
will allow correction of single bit errors, detection of double bit
errors.

      The design extends the capability of the Test Block (TB)
instruction to dynamically test the data portion of the key detect if
a correctable error persists.  If it does, then a bad block condition
code is returned for the Test Block instruction.  This prevents usage
of a storage key that might be subject to a double bit error.  If no
errors are detected, then normal operation continues.

      A combination of hardware and microcode is implemented so as to
report to a Test Block instruction the presence of a correctable, but
permanent, error in a set of Storage Protection Keys.

      The hardware, using an error correction code on a block of
keys, detects the presence of a single error and reports this event
to the microcode, at the same time attempting to correct the error in
place.

      The microcode, upon this notification, rechecks the keys and,
if the error still persists, returns to the Test Block instruction
the appropriate condition code indicating a problem which may develop
subsequently into an uncorrectable error situation and damaged
storage.

      The diagnostic function operates automatically and in-line with
no performance impact to the Test Block i...