Coupling different methodologies to validate obsolete microprocessors

The actual operating life time for many electronic systems turned out to be much longer than originally foreseen, leading to the use of obsolete components in critical projects. To skip microprocessor obsolescence problems, companies should have bought larger stocks of components when still available, or are forced to find parts in secondary markets later. Alternatively, a suitable low-cost solution could be replacing the obsolete component by emulating its functionalities with a programmable logic device. However, design verification of microprocessors is well known as a challenging task. This paper proposes a coupled methodology to generate test-programs, using complementary techniques: one pseudoexhaustive and one driven by an evolutionary optimizer. As a case study, the Motorola 6800 was targeted.