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Reducing N**2 Test Patterns for Arrays

IP.com Disclosure Number: IPCOM000102135D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 32K

Publishing Venue

IBM

Related People

Monzel, JA: AUTHOR [+2]

Abstract

Most defects in a memory's true complement generators and word decoders that are detected by using a N**2 test pattern fail under one of two conditions: 1) all the address bits change between the home and the away address 2) only a single bit changes between the home and away address. It is possible to develop tests that meet these two conditions with significantly fewer patterns than a N**2 pattern set, with an extremely small increase in SPQL, if any. Two tests are needed to replace the N**2 pattern. One test switches all the address bits and is order of N, where N is the number of address lines exercised in the N**2 test. The other test switches a single address bit at a time, and is order of N log2N.

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Reducing N**2 Test Patterns for Arrays

       Most defects in a memory's true complement generators and
word decoders that are detected by using a N**2 test pattern fail
under one of two conditions:  1) all the address bits change between
the home and the away address 2) only a single bit changes between
the home and away address.  It is possible to develop tests that meet
these two conditions with significantly fewer patterns than a N**2
pattern set, with an extremely small increase in SPQL, if any.  Two
tests are needed to replace the N**2 pattern.  One test switches all
the address bits and is order of N, where N is the number of address
lines exercised in the N**2 test.  The other test switches a single
address bit at a time, and is order of N log2N.
      Given the following N**2 test:
      Do I=1 to N
           Write Address(I) Background
      End Do
      Do Home=1 to N
           Write Address(Home) Background
           Do J=1 to N
                Read Address(Home)
                Read Address (J)
           End Do
           Write Address(Home) Background
      End Do
      It should be replaced by the following:
      Do I=1 to N
           Write Address(I) Background

      End Do
      Do I=1 to N
           Write Address(I) Background
           Read Address(I)
           Read Address(...