To develop an operating system from scratch is an invincible problem for most students – but starting at already finished base will never disclose them what the operating systems are about.

MSIM is a light-weight computer simulator based on MIPS R4000 and RISC-V. It is used for education and research purposes, mainly to teach the construction and implementation of operating systems. MSIM is distributed with source code under the GNU GPL license to make possible modifications for users and works on most POSIX-compliance environments (mainly GNU/Linux, Mac OS X, but can be also compiled in Cygwin or MinGW in Windows). The user interface is simple terminal-style.

MSIM provides following features (along others):

MSIM does not aim to be a speed-optimized real hardware simulator, but rather a fully deterministic simulator useful for kernel debugging.

More details and documentation can be found at