Graphcore Limited

Natalie Narkonski

Philip Horsfield

Stephen Felix

A method for repairing a processor. The processor comprises a plurality of processing units and an exchange comprising a plurality of exchange paths for transmitting data between the processing units. Each processing unit is connected to output data to a respective exchange path. An exchange path functional test of at least a portion of the exchange paths is carried out. Based on the exchange path functional test, it is identified that one or more of the exchange paths is defective, and the processing units connected to the one or more defective exchange paths is identified. The identified processing units are switched out of functional operation of the processor and switching in at least one repair processing unit connected to a non-defective exchange path for functional operation of the processor.

Scan testing in a processor

A processor comprises an exchange, a plurality of columns, and a plurality of exchange scan chains. The exchange comprises a plurality of exchange paths, each comprising a set of exchange path portions, for transmitting data between processing units. Each of the plurality of column comprises processing units, each processing unit connected to output data to a respective exchange path, and column pipe circuitry for providing a controllable path between the exchange and the processing units. The column pipe circuitry comprises a column wrapper chain for preventing a scan test signal from passing between the exchange paths and the processing units. The exchange scan chains enable scan testing of the exchange paths. Each exchange scan chain comprises a plurality of scan chain segments, each scan chain segment comprises an exchange path portion connected to at least one of the processing units of at least one of the columns of the processor.

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Bristol, United Kingdom

Natalie Narkonski