Abstract: A method and apparatus for locating the source of first error in a high speed synchronous system having a plurality of potential sources for first error is disclosed. An error-report collecting cell is provided having a plurality of self-freezing error history latches each including an output coupled to an report-condensing OR gate and a first-error code storing register. The report-condensing OR gate freezes a code value stored in the code register upon receipt of a first error report. The frozen code identifies the source of the first received error report. The report-condensing OR gate further initiates a clock counter upon receipt of the first error report. When system clocks stop, the contents of the clock counter indicate the number of clocks occurring between stoppage and receipt of the first error report by the cell. An error communication network is formed comprising a plurality of the above-described cells each receiving an error report either directly from an error detector or from another cell.

Abstract: The invention provides a method and apparatus for generating a signature signal which indicates a probable location for an error-causing mechanism within a digital system, where the digital system has control-signal and data-signal carrying busses and error detection means for detecting error conditions in the signals carried by those busses. The signature generating method comprises the steps of: counting the total number of errors detected by the error detection means during a signature generating run; and counting the number of errors detected by the error detection means during a signature generating run where those errors were accompanied by the presence of accompanying signals on the signal-carrying busses, the accompanying signals being ones which belong to a predefined subset of all signals appearing on the system signal-carrying busses.