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Testing Logic and Storage Network

IP.com Disclosure Number: IPCOM000085865D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Steffner, WR: AUTHOR

Abstract

When logic and storage circuits are highly integrated in a semiconductor device, it is difficult to perform all of the circuit tests that might show a fault in the device. To simplify this testing, it is conventional to organize such a circuit into circuit groups that can be individually tested. In one arrangement for subdividing a circuit, a latch is provided for each group of combinatorial logic circuits. These latches are accessible to test programs and diagnostic programs.

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Testing Logic and Storage Network

When logic and storage circuits are highly integrated in a semiconductor device, it is difficult to perform all of the circuit tests that might show a fault in the device. To simplify this testing, it is conventional to organize such a circuit into circuit groups that can be individually tested. In one arrangement for subdividing a circuit, a latch is provided for each group of combinatorial logic circuits. These latches are accessible to test programs and diagnostic programs.

To further simplify this testing, a matrix illustrated in the drawing is formed to show the relationship of these latches. A 1 in a row in the matrix represents the connection of the output of the latch of the row heading to an input of the latch of a column heading. A 0 signifies that the output of a latch of a row heading is not connected to the input of a latch of a column heading. Thus, an area in the matrix having dense 1 entries shows that particular latches are closely related, and these latches can be combined as a larger, multilatch unit for tests. (Rows can be interchanged and columns can be interchanged to form optimum groups.) An example is shown in the drawing enclosed within dashed lines.

When a test is organized according to the matrix of the drawing, a number of latch groups can be tested together as a unit so that only a few tests will be necessary on the larger, multilatch unit, if in fact it does not have a fault. When a fault is found wi...