A simulator is a software development tool that runs on a PC and simulates the functionality of an MCU. Because it represents the MCU architecture and logical instructions, the simulator provides a good environment for debugging logical code when the target hardware is not yet available. In this way, the simulator helps reduce overall embedded system development time. The H8S Simulator offers a range of functions that includes CPU instructions, memory access, and register access. Because simulators provide logical instructions but not the physical gate construction of a real MCU, they cannot easily emulate peripheral modules. However, various features are implemented in the HEW IDE (Integrated Development Environment) that complement the H8S Simulator to make the environment more “hardware-like”. These features include simulated I/O, Trigger, and TCL Toolkit.