Browse Prior Art Database

Optical Logic Analyzer

IP.com Disclosure Number: IPCOM000089517D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Brosch, R: AUTHOR [+5]

Abstract

For testing LSI (large-scale integration) logic circuits an optical display is proposed. The display is performed on a television screen or by an LED (light-emitting diode) matrix. Each optical display point has its associated logic circuit on the chip. The display can be of a physical image of the chip or a numerical order representation.

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Optical Logic Analyzer

For testing LSI (large-scale integration) logic circuits an optical display is proposed. The display is performed on a television screen or by an LED (light- emitting diode) matrix. Each optical display point has its associated logic circuit on the chip. The display can be of a physical image of the chip or a numerical order representation.

Fig. 1A shows logic chip 1, having four inputs I1 - I4 and three outputs 01 - 03 which is to have twelve logic circuits. Fig. 1B shows the chip image on screen 2. During testing the chip first receives the input pattern shown in Fig. 1C, and the output pattern received is compared with a nominal output pattern. If there is a match, the raster points corresponding to the logic circuits on the chip are only faintly illuminated. If the output patterns expected and received do not match, the raster points of those logic circuits are brightly illuminated which are connected to the output showing the erroneous output bit.

Fig. 1C shows that three raster points S1, S7 and S8 are brightly illuminated. This means that all or, at least, one of the corresponding logic circuits is defective. The raster points S5, S7, S10 and S12 (Fig. 1D), which are brightly illuminated upon the application of the input pattern, indicate that all or, at least, one of the respective logic circuits is defective. Since raster point S7 is brightly illuminated, upon the application of both input patterns, it is highly probable that the c...