Image forming apparatus

An image forming apparatus adapted to be connected with an external device, comprising:

• a printer controller, operable to convert image data received from the external device into image information;
• a print engine, adapted to perform printing on a printing medium;
• and
• an engine controller, operable to cause the print engine to perform the printing in accordance with the image information, and to communicate data regarding a status of the print engine with the print controller by a serial communication, wherein:
• the printer controller and the engine controller perform an activation sequence including an operation for stabilizing circuits provided therein;
• the engine controller performs an initializing operation for placing the print engine in a printable condition after the completion of the activation sequence;
• the printer controller periodically transmits first data inquiring the status of the print engine to the engine controller during the initializing operation;
• the engine controller is configured to transmit second data indicating the status of the print engine to the printer controller in response to the first data;
• and
• the engine controller is configured to spontaneously transmit third data indicating that a change is occurred in the status of the print engine to the printer controller after the completion of the initializing operation.