| 摘要 |
A 25-pin cable socket has serial pins and parallel pins. Pins 18 through 25 are at ground level only if a parallel cable is inserted in the socket. Serial communication lines are provided to a serial controller and parallel communication lines are provided to a parallel controller. A OR is connected to the pins 18 through 25. A switch is connected to the output of the OR. If ground is sensed at the pins 18 through 25, the OR output is asserted causing the switch to be activated to connect the parallel pins associated with parallel operation to the parallel communication lines. If ground is not sensed at the pins 18 through 25 the switch is deactivated to connect the serial pins associated with serial operation to the serial communication lines.
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