Method and apparatus for locating source of error in high-speed

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. After clock stoppage, a scan means inspects the contents of all error history counters to locate the cell with the highest count. This is indicated as the cell which received the earliest error report. The scan means further inspects the code storing register of that cell to identify the exact source of the first error.