THIS ARTICLE PRESENTS A FAST AND ACCURATE INTERVAL-BASED CPU TIMING MODEL THAT IS EASILY IMPLEMENTED AND INTEGRATED IN THE COTSON FULL-SYSTEM SIMULATION INFRASTRUCTURE. VALIDATION AGAINST REAL X86 HARDWARE DEMONSTRATES THE TIMING MODEL'S ACCURACY. THE END RESULT IS A SOFTWARE SIMULATOR THAT FAITHFULLY SIMULATES X86 HARDWARE AT A SPEED IN THE TENS OF MIPS RANGE.