Information processing system provided with self-diagnosing circuit and

Abstract

An information processing system composed of a plurality of circuit blocks operative in an normal operation mode and in a self-diagnosis mode comprises: a clock signal generating circuit for generating a basic clock signal in the normal operation mode, and a first clock signal with a period. N times (N=2, 3, . . . ) as long as that of the basic clock signal and a second clock signal out of phase from the first clock signal by a delay less than one cycle of the first clock signal in the self-diagnosis mode; a memory for storing microinstructions for self-diagnosis operative in synchronism with the basic clock signal in the normal operation mode, and in synchronism with the first clock signal in the self-diagnosis mode; a decoder for inputting and decoding the mlcroinstructions for self-diagnosis stored in the memory; a test data generating circuit for generating test data in accordance with the decoded results obtained by the decoder in synchronism with the first clock signal at the self-diagnosis mode; first type circuit blocks operative in synchronism with the basic clock in the normal operation mode, for storing test data generated by said test data generating means In synchronism with the second clock and outputting test data therein In synchronism with the first clock In the self-diagnosis mode; second type circuit blocks for outputting output data corresponding to the test data provided in synchronism with the basic clock signal in the normal operation mode, and in synchronism with the first clock in the self-diagnosis mode; and a signature compressing circuit for inputting the test resultant data outputted from the circuit blocks to diagnose the operation of the circuit blocks, in synchronism with the second clock signal in the self-diagnosis mode.