The SimulAVR program is a simulator for the Atmel AVR family of
microcontrollers (ATtiny and ATmega). SimulAVR can be used either
standalone or as a remote target for avr-gdb. There is a python
and TCL interface. When used in gdbserver mode, the simulator is used
as a back-end so that avr-gdb can be used as a source level debugger
for AVR programs.

SimulAVR started out as a C based project written by Theodore Roth
in 2001. Klaus Rudolph started then in 2004 to rewrite the hardware
simulation part in C++. Only the instruction decoder and the avr-gdb
interface are mostly copied from the original simulavr sources.
This C++ based version was known as simulavrxx until it became
feature compatibile with the old simulavr code, then it
was renamed back to simulavr.