| 摘要 |
PROBLEM TO BE SOLVED: To smoothly transmit data while using an analog telephone line without depending on the operation of an operating system. SOLUTION: When a data amount stored in a receiving FIFO 11 reaches a first setting value, a FIFO control part 15 generates a first interruption to a CPU 1 and when a data amount stored in a transmitting FIFO 12 gets less than a second setting value, on the other hand, a second interruption is generated to the CPU 1. When the first interruption is received, the CPU 1 transfers all the data stored in the receiving FIFO 11 to a data bus buffer 16 so that the receiving FIFO 11 is made empty and when the second interruption is received, on the other hand, data to be transmitted are transferred to the transmitting FIFO 12.
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