Semiconductor integrated circuit with self-test function

Claim 1

A semiconductor integrated circuit with a port for receiving data from and outputting data to an outside source and having a self-test function for testing functional internal blocks contained in the semiconductor integrated circuit without the need to input data from an outside source, comprising: an internal data bus; a memory for storing a self-test program and prediction value data for testing each internal functional block; random number generating means for generating test data; data selecting means having a first input coupled to said port and a second input coupled to said random number generating means and an output coupled to said internal data bus for outputting the test data generated by said random number generating means to said data bus in place of data input from the outside source via said port when said self-test program is executed; self-test initiating means for initiating said self-test program in response to an external signal, wherein the self-test program tests each functional block using the test data output from said data selecting means and outputs a test result to the data bus; and comparison means coupled to the data bus for comparing the test result output to said data bus by executing said self-test program with said prediction value data and outputting a compared result to the outside source.