Communication device, communication method and medium on which computer program for carrying out the method is recorded

Transmit data generated in processes in which a utilization portion 20 performs arbitrary application processing are transmitted to an exterior in accordance with a previously determined protocol in a control portion 10. A RAM 30 comprises a transmission buffer 34 and a management table 35 for managing a state where each of the transmit data, whose request for transmission has been accepted by the control portion 10, is transmitted and the location, on the transmission buffer, of the transmit data. The utilization portion 20 outputs, when the transmit data is generated, a request to acquire a data write area to the control portion 10. Correspondingly, the control portion 10 refers to the management table 35, to specify a data write area where writing is newly allowed in the transmission buffer 34 and present the specified data write area to the utilization portion 20. The utilization portion 20 writes the transmit data into the presented data write area. The RAM 30 comprises an area 51 managed by the control portion 10 and an area 9i managed by a utilization portion 2i (i = any one of 1 to N). The control portion management area 51 comprises a first receiving buffer 81, a second receiving buffer 6i and a busy flag 7i. Each of the utilization portion management area 9i comprises a data transcription area 9ia. The control portion 10 writes the received data into the first receiving buffer 81. In then transcribing the data written into the first receiving buffer 81, the control portion 11 confirms a state where the utilization portion 2i which is the destination of the data is used using the busy flag 7i. The utilization portion 2i is notified to transcribe the data onto the second receiving buffer 2i when the busy flag 7i is OFF, while transcribing the data onto the data transcription area 9ia when it is ON.