1. A method for recording core data of a computer process, wherein the computer process is arranged to provide trace data, the method comprising the steps of: storing a first set of core data comprising an image of a memory for the computer process in response to a first set of trace data being produced for the computer process for a first trace point; and storing a second set of core data in response to a second set of trace data being produced for the computer process for a second trace, wherein the second set of core data comprises a record of any change in current memory contents for the computer process with respect to the first set of core data.