SPIM is a MIPS processor simulator, designed to run assembly language code for this architecture. The program simulates R2000 and R3000 processors, and was written by James R. Larus. The MIPS machine language is often taught in college-level assembly courses, especially those using the textbook Computer Organization and Design: The Hardware/Software Interface by David A. Patterson, John L. Hennessy, and Nitin Indurkhya (ISBN 1-55860-428-6).
SPIM simulators are available for Windows (PCSpim), Mac OS X and Unix/Linux-based (xspim) operating systems.
The name of the language is a reversal of the letters "MIPS".