The image forming apparatus having a power saving mode

An image forming apparatus includes a communication interface receiving data; a buffer storing the data; a main system processing the stored data; a subsystem controlled by the main system to perform a function of the image forming apparatus; a system control unit; and a data processing unit. The system control unit switches an operation status mode of the image forming apparatus between a normal status mode and a deep sleep status mode. When the image forming apparatus is in the deep sleep status mode, the data processing unit processes the data received from the buffer if the data is determined to be processable by the data processing unit and causes the system control unit to switch the operation status mode from the deep sleep status mode to the normal status mode if the received data is determined not to be processable by the data processing unit.