Applied Microsystems Corporation

William O Swan

Eugene M Zumchak

A device and process for identifying signals in microprocessors-based circuits includes a probe, a display a target interface and a control system based on a similar microprocessor. Sets of signal patterns are impressed on lines in the target system. The patterns are selected so as to create unique signatures for all data lines, address lines, control lines, combinations of control lines and their complements. To associate the node with a data line, a signal pattern is written to a single address in the target system. After the pattern is impressed the signature of the response is compared with a table of responses that would be expected. If it is not identified, then the target system is subjected to a series of read functions. The address from which the data is read is determined by a second stimulus pattern. After the read operations, the signature of the response at the node is compared with expected signatures. If no match is found, then an attempt is made to associate the node with system control lines or combinations of those lines by impressing a third pattern on the system control lines. The stimulation sequence is repeated several times. The signature at the node is compared with expected signatures. If the signature match is not found in any of the above steps the identity of the associated line or combination of lines is indicated. If it is not, then the signature itself is displayed.

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King County, WA, United States of America

William O Swan