An In-Circuit Emulator (ICE) developer designs and implements software and hardware tools for testing and debugging embedded systems. They work with microprocessors and microcontrollers, creating an emulation system that operates in sync with the device under test. ICE developers write software code to replicate device operations, analyze system performance, and identify potential issues. They also design hardware interfaces to connect the emulator to the target system, allowing real-time monitoring and modification of the system's operation. This work requires a deep understanding of digital electronics, programming, and system architecture, aiding in the development and troubleshooting of complex electronic systems.