Electronic system for electronic device

An electronic system supporting narrowband internet of things (NB-IoT), the electronic system comprising:

• a NB-IoT circuit;
• a communicator;
• a shared central processor to control the NB-IoT circuit or the communicator;
• a shared memory to store data or code for the shared central processor, the shared memory being connected directly to the communicator and including a shared main memory and a shared nonvolatile memory;
• and
• an external storage device to transmit and receive the data or the code to and from the shared central processor and the shared memory,
• wherein the NB-IoT circuit has an idle period in which the NB-IoT circuit does not transmit or receive the data or the code, the communicator transmits or receives the data or the code in the idle period, and the NB-IoT circuit and the communicator use the shared central processor at different times from each other, without using the shared central processor at the same time.