An electronic apparatus is provided, which includes a central processing unit (CPU), a first memory unit which performs communication with the CPU, and a second memory unit which stores therein conditional access system (CAS) software and platform software. According to the method of controlling the apparatus, upon booting, the CPU copies the CAS software to an internal memory area which may be within the CPU, copies the platform software to the first memory unit and executes the CAS and platform software, and executes CAS operations through communication between the CAS software and the platform software.