A MIPS R2000/R3000 Simulator

James Larus

Old Address Current Address
Computer Sciences Department
1210 West Dayton Street
University of Wisconsin
Madison, WI 53706
Microsoft Research
One Microsoft Way
Redmond, WA 98052


spim is a self-contained simulator for running MIPS R2000/R3000 assembly language programs. It reads and immediately executes assembly language code for this processor. spim provides a simple debugger and simple set of operating system services.

spim implements almost the entire MIPS assembler-extended instruction set for the R2000/R3000 (It omits some of the complex floating point comparisons and details of the memory system page tables.) The MIPS architecture has evolved considerably since then (in particular, from 32 to 64 bits), which means that spim will not run programs compiled for recent MIPS or SGI processors.

spim comes with complete source code and documentation. It also include a torture test to verify a port to a new machine.

spim implements both a simple, terminal-style interface and a visual windowing interface. On Unix, the spim program provides a terminal interface and the xspim program provides an X window interface. On PCs, the spim program provides a DOS interface or console interface and PCSpim provides a Windows interface..

Downloading SPIM

Platform   Form File
Unix or Linux system spim
Source code http://www.cs.wisc.edu/~larus/SPIM/spim.tar.Z or
Microsoft Windows
(Windows 95, 98, NT, 2000)
Executable http://www.cs.wisc.edu/~larus/SPIM/pcspim.zip
Source code http://www.cs.wisc.edu/~larus/SPIM/pcspim_src.zip
Microsoft DOS spim Executable http://www.cs.wisc.edu/~larus/SPIM/spimdos.exe

To run spim or xspim on a Unix or Linux system, copy either the compressed tar file (http://www.cs.wisc.edu/~larus/SPIM/spim.tar.Z) or the gzip'ed tar file (http://www.cs.wisc.edu/~larus/SPIM/spim.tar.gz).  Both files contains source and must be compiled for a particular platform.

To run PCspim on a PC under Microsoft Windows, download the file http://www.cs.wisc.edu/~larus/SPIM/pcspim.zip, unzip it, and run setup.exe (instructions: postscript.).

Source for the PC version (both PCspim and spim) is available separately in the file ftp://ftp.cs.wisc.edu/pub/spim/pcspim_src.zip

To run spim on a PC under MS/DOS, copy the file http://www.cs.wisc.edu/~larus/SPIM/spimdos.exe

There is no Macintosh version of spim (Yes, there should be).


Morgan Kaufmann has generously provided an on-line version of Appendix A from Hennessy & Patterson, Computer Organization and Design: The Hardware/Software Interface (as a Adobe PDF file). This is a more complete and up-to-date version of spim documentation included with spim.

The documentation included with spim is also online (as a postscript or Adobe PDF file). However Appendix A of Hennessy & Patterson, Computer Organization and Design: The Hardware/Software Interface, is a more complete and accurate description of the MIPS architecture and spim software.

There is some documentation for the Windows interface to spim: postscript or Adobe PDF file.

The reference manual for the MIPS architecture (including processors later than the R2000/R3000) is: Gerry Kane and Joe Heinrich, MIPS RISC Architecture, Prentice Hall, Englewood Cliffs, N.J. 07632 ISBN 0-13-1059254.

Another good book for MIPS R2000 and R3000 programmers is: Erin Farquhar and Philip Bunce, The MIPS Programmer's Handbook, Morgan Kaufmann, San Francisco, CA, 1994, ISBN 1-55860-297-6.

However, the best book for MIPS programmers is: Dominic Sweetman, See MIPS Run, Morgan Kaufmann, San Francisco, CA, 1999, ISBN 1-55860-410-3.

Latest Version

The current version of spim is 6.4, which contains the following changes from version 6.3:

The previous version of spim is 6.3, which contains the following changes from version 6.2:


spim is copyrighted by James Larus. The DOS and Windows ports were done by David A. Carley and are copyrighted by Morgan Kaufmann Publishers. spim can be freely used and distributed for non-commercial purposes (see the README file for details).


spimsal is an old version of spim that ran on PCs running Windows 3.1 and Macintoshes. spimsal implements an extended version of the MIPS instruction set and is based on an old version of spim. It also does NOT run under Windows '95 or Windows NT. If you used this program on PCs and do not need the SAL instructions, you should get the new version.