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Better Error Detection And Isolation Using an Alternate Decoder Output Approach

IP.com Disclosure Number: IPCOM000101954D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Christiansen, RA: AUTHOR [+2]

Abstract

This article describes a technique for using a decoder to help detect errors by spreading the outputs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 85% of the total text.

Better Error Detection And Isolation Using an Alternate Decoder Output Approach

       This article describes a technique for using a decoder to
help detect errors by spreading the outputs.

      This is a reliability, availability, and serviceability (RAS)
technique dealing with high availability to the end user.  When
designing a decoder and spare cells are available, it is a good RAS
design approach to have the good outputs on even or odd decodes and
error decodes on the opposite outputs.  In that way any picked or
dropped decode errors will produce a decoder error to the system
which can then isolate the fault.

      Control logic  that can detect its own errors is very difficult
to design.  Decoders are used extensively in control logic and the
detection method disclosed herein is very useful in finding control
logic errors.  It does require that the decoder be larger in design
but with denser logic.  Most designs are I/O bound and not cell count
restricted.

      The drawing is a functional block diagram of the decoder
illustrating how to spread the outputs.  Only four outputs are needed
so an extra level of decode is added that provides eight outputs so
that each good decode is separated by a bad output.  Any error in the
decoder in picking or dropping inputs or any race conditions will
decode an error and the system will not finish the operation.  This
gives the control logic around the decoder plus the decoder high
error detection capab...