SIMH is a historical computer simulation system. It consists of simulators for approximately 20 different computers, all written around a common user interface package and set of supporting libraries. SIMH can be used to simulate any computer system for which sufficient detail is available, but the focus to date has been on simulating computer systems of historic interest.
Avrora is a set of tools for programs that run on the AVR series of microcontrollers produced by Atmel. It contains a flexible framework for simulating, analyzing, and optimizing assembly programs, and provides a clean Java API and infrastructure for experimentation, profiling, and analysis.