Great site for the entire computer architecture community; professionals, academics and graduate students. You will find many interesting links on this site.
SPIM is a self-contained simulator that will run MIPS32 assembly language programs. It reads and immediately executes assembly language code for this processor. SPIM provides a simple debugger and minimal set of operating system services.
mic1 is a Java-based simulator which implements the Mic-1 microarchitecture described in Chapter 4 of Andrew S. Tanenbaum, Structured Computer Organization, Fourth Edition (Prentice-Hall, 1998).