FlightGear Flight Simulator: free open-source multiplatform flight sim
Realtime PC-based control and simulator of control systems
IEC 104 Source code Library for Windows, Linux, QNX, Real time OS, ARM
IEC 101 Source code Library Windows Linux POSIX - c, c++, c# .net
The classic RPL programming language reimplemented and reimagined.
Simulate your IO with the Arduino Simulator
Simulate your IO with this Arduino Simulator
Matlab/Scilab-FEMM based GUI to Assist the Design of Permanent Magnet
Modbus slave simulator
PPface is vector processor emulator / simulator
RetroPC-SIM is an Arduino project to help to understand how pc works
Open source model airplane simulator
Circuit simulators like SPICE for low memory computers
A simulator for Atmel's 8/16-bit AVR microcontrollers
Multithreaded N-Point Gravity Simulation for PC and Android
Various TCP/IP servers, clients and network management tools
SDK for the SARK-110 Antenna Analyzer
A MultiMedia Logic Design System
To be a practical Arduino simulator