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Automatic Fault Isolation for Digital Assemblies

IP.com Disclosure Number: IPCOM000076978D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 105K

Publishing Venue

IBM

Related People

Elmore, JM: AUTHOR [+2]

Abstract

Two techniques are shown for the automatic fault isolation for digital assemblies, utilizing Good Machine Response (GMR) and Failing Machine Response (FMR) for successful fault isolation. Failure Isolation Mode 1:

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Automatic Fault Isolation for Digital Assemblies

Two techniques are shown for the automatic fault isolation for digital assemblies, utilizing Good Machine Response (GMR) and Failing Machine Response (FMR) for successful fault isolation. Failure Isolation Mode 1:

As shown in the Fig. 1 flow chart, this test mode uses the good machine test data resident in memory and the failing machine test data from the test tape. Failure isolation is achieved by processing the failure data for each test step as testing takes place. A failure table is constructed in core and as testing is performed, failures are eliminated in the following manner. 1. If a test passes, all failures detected by the test are eliminated from the failure table. 2. If a test fails, a match is sought between the Unit Under Test (UUT) response and a failing machine response for the test in the result record on the test tape. a) If a match is found, all failures detected by UNMATCHED failing machine responses (FMR) for the test are eliminated from the failure table - the failures detected by the matched FMR are not eliminated from the failure table. b) If a match is not found, none of the failures detected by the test are eliminated and the UUT response and test number are stored for possible future use.

As testing progresses, the number of failures in the failure table will continue to diminish until, at test conclusion, only those failures that were detected by EVERY failing test remain. The location, on the UUT, of these failures is then determined by comparing the failure table and the DCTNRY record on the test tape.

In this test, relatively small amounts of data are handled thereby requiring less storage and direct availability of failing component locations. Failure Isolation Mode 2:

As shown in the flow chart of Fig. 2, this test mode uses the good machine test data resident in the control-computer memory and the failing machine test data from the test tape. Fault Isolation is achieved by processing the failure data for each failed test in the following manner. 1. If a test fails, a match is sought between the UUT response and a failing machine response for the test in the result record on the test data tape. a) If a match is found and this is the first test to fail, all of the failures associated with the matched failing machine response are stored in the control-computer memory and a counter is assigned to each failure. Each counter is incremented to a value of one. The UUT response is stored for possible future use. b) If a match is found and this is not the first failed test...