Circuit structure for testing microprocessors and test method thereof

摘要

A test circuit is capable of testing functions of a microprocessor without involving any performance penalty or substantial increase in area overhead. The test circuit includes a test control register for providing test instructions to an instruction decoder of the microprocessor, a first multiplexer for selecting either the test instructions from the test control register or instructions from an instruction fetch unit, a linear feedback shift register for providing test operand to an instruction execution unit of the microprocessor wherein the test operand is random data for executing the instruction execution unit multiple times per instruction from the test control register, a second multiplexer for selecting either the test operand from the linear feedback shift register or operand from the main memory, a multi-input feedback shift register for receiving results from the instruction execution unit, and a controller for providing the test instruction to the test control register and the linear feedback shift register and evaluating an output signature of the multi-input feedback shift register.