1. A method of in circuit emulation of an integrated circuit including a digital data processor capable of executing program instructions, comprising the steps of: detecting a first debug event during normal program execution; upon detection of the first debug event suspending normal program execution while permitting at least one type interrupt service routine executed in response to a corresponding interrupt; incrementing a debug frame counter upon each of the at least one type interrupt received while suspending normal program execution; decrementing the debug frame counter upon each return from interrupt received while suspending normal program execution; detecting at least one second debug event during an interrupt service routine executing while suspending normal program execution; upon detection of the second debug event suspending program execution of the interrupt service routine while permitting execution of other interrupt service routines in response to corresponding interrupts; and storing the count of said debug frame counter upon each second debug event.