PURPOSE: To enrich a diagnostic side face of a program of a data processing system by setting a trigger point of a lot of optional parts at the same time point, when diagnosing a program of a CPU to be inspected.

CONSTITUTION: When a start command is given to an analyzer box, it is switched to a data trace mode circuit by a command of a controlling CPU30. As for this circuit, an address counter 50 designates as address to data tracing RAMs 24W26, and an output of a CPU to be inspected 300 is stored in a memory, respectively. At the same time, each signal of data, address and status of the CPU300 is inputted to controlling RAMs 21W23, compared with an already stored trace signal, and outputted to a coincidence detecting circuit 40. A coincidence signal is informed to the CPU30, and in accordance with a data collecting range designated by an analyzing mode data, an optional number of signals before and after the discriminated signal of the CPU to be inspected 300 are designated as a collected data.