| 摘要 |
PURPOSE:To use a key switch as a key for a personal computer main circuit side by using a photocoupler so as to couple the personal computer main circuit and a telephone set circuit so as to eliminate the need for a dialing IC of the telephone set circuit. CONSTITUTION:The personal computer main circuit 1 and the key switch section 2 of the telephone set are coupled by a photocoupler 3 and an interface circuit 11 receiving a clock from the personal computer main circuit 1 and scanning sequentially the key switch is provided on the key switch section 2, on the other hand, the key switch information detected attending with the scanning is inputted to the personal computer main circuit 1 via the photocoupler 3 and sent to a telephone circuit through a dialing circuit 7 of the personal computer main circuit. Thus, the electric isolation of both circuits is ensured sufficiently, the dialing circuit for the telephone set circuit side is not required and the key switch for the telephone set side is used as the key of the personal computer main circuit side.
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