chARM is a Real-Time Operating System developed from scratch that runs on ARM platform. chARM implements Earliest Deadline First (EDF) scheduling algorithm. Its periodic threading model allows creating tasks with arbitrary period, budget, deadline and phase having granularity of few microseconds. It attempts to reduce the context switch time to absolute minimum when periodic tasks finish before their deadline by not storing all registers. chARM currently runs on TQ2440 development board that has Samsung's S3C2440? SOC. Eventually I intend to add support for MPU and MMU.