| 摘要 |
PURPOSE:To always execute a normal data transmission without executing clock switching by a person's help by selecting automatically a clock signal used in accordance with a data processing terminal equipment. CONSTITUTION:A MODEM device is provided with an internal oscillator 21, a clock switching circuit 22, and a communication control circuit 23. In this MODEM device, in the case it is set to an automatic mode, in accordance with whether a clock signal ST1 is supplied from a data processing terminal equipment or not, an input clock of the communication control circuit 23 is selected automatically. Accordingly, in accordance with the data processing terminal equipment, the clock signal to be used can be selected so as to always coincide between the data processing terminal equipment and the MODEM device. In such a way, a normal data transmission can always be executed without executing clock switching by a person's help. |
