Efficient instruction level simulation of computers

A technique for creating efficient, yet highly accurate, instruction level simulation models of computers is described. In contrast to traditional approaches that use a software interpreter, this technique employs direct execution of application programs on the host computer. An assembly language program for the machine to be modeled is decompiled to a high level language, instrumented, and then recompiled and executed on the host computer. A prototype implementation modeling the Motorola MC68010 microprocessor is described, and the efficiency and accuracy of this prototype is reported. It is demonstrated that the direct execution technique can be used to produce accurate simulation models which are orders of magnitude faster than traditional, register transfer level simulators.