1. A method comprising: receiving at a program memory and a patch memory a request address from a requester; generating a program data value from the program memory based on the request address; returning to the requester, in place of the program data value, a patch data value recorded in association with the request address in the patch memory, if the request address is matched in the patch memory, the patch data value being returned to the requester in no more time than the program data value would have been returned to the requester if the request address was not matched in the patch memory.