Abstract: A processing device performs operations in response to program instructions. In particular, values are written to a data memory of the system, which alters a defined visible state of the system. In the event of an exception (e.g. a pagefault or TLB miss in a virtual memory system), control returns to a recent checkpoint instruction after handling the exception, and instructions are re-executed. A record/replay circuit is provided in the form of an event memory, which remembers only those values read from the data memory since the last checkpoint. During the re-execution, the recorded values are reproduced instead of performing actual memory reads, and all memory accesses are suppressed. When the re-execution reaches the point where execution was originally interrupted, recording begins again to prepare for any further exception which may arise before the next checkpoint.