Amdahl Corporation

Patricia A Simonson

Richard H Larson

Jeffrey A Techau

Timothy S Koepp

David T Ino

An apparatus and method for forcing stuck-at and transient errors at sequential and combinational logic and signal lines in a large scale data processing system. Error forcing is achieved by including a scan-in gate with error input and address lines for each scan point to be tested. A fault signal of adjustable duration is generated and combined in a unique fashion to an existing scan-in signal to permit either stuck-at or transient errors to be forced.

Apparatus and method for forcing hardware errors via scan

Described is a digital phase lock device comprising a feedback loop having a plurality of delay elements and a selector. The delay elements delay a sampling signal into signals having different time delay values relative to the sampling signal. These delay signals are compared with a periodic target signal whereby one of them is selected as the next sampling signal. As a result, the sampling signal tracks the periodic signal.

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San Jose, CA, United States of America

Patricia A Simonson