Patent ID: 10910082

Abstract:
Apparatus comprises memory circuitry having a plurality of addressable memory entries storing respective data items and associated error protection codes; memory error protection circuitry to generate the error protection code for a data item stored to the memory circuitry, the error protection code for a given data item stored to the memory circuitry depending upon at least the given data item and a memory address defining a memory entry to which the given data item is stored, and to perform a check operation to check for consistency between a retrieved data item, the memory address defining a memory entry from which the given data item is retrieved and the error protection code associated with the retrieved data item; memory built-in self-test circuitry to test the memory and memory error protection circuitry; and access circuitry to provide an indirect access path between the memory built-in self-test circuitry a memory which accesses the memory circuitry via the memory error protection circuitry and a direct access path between the memory built-in self-test circuitry and a memory entry which bypasses the memory error protection circuitry; the memory built-in self-test circuitry being configured to execute a test operation by writing a test value to a first memory entry of the memory circuitry having a first test memory address via the indirect access path; retrieving the test value and associated error protection code from the first memory entry by the direct access path; writing the retrieved test value and associated error protection code to a second memory entry having a second test memory address via the direct access path, there being a difference in at least one bit between the first test memory address and the second test memory address; and retrieving the test value and associated error protection code from the second memory entry via the indirect access path; the memory built-in self-test circuitry comprising fault detection circuitry configured to detect a fault condition when the result of the check operation performed by the memory error protection circuitry is inconsistent with the difference between the first test memory address and the second test memory address.