| 摘要 |
PURPOSE:To prevent data transmission from being blocked by feeding back the output of a priority encoder to a gate circuit and controlling the set of a flip-flop by a request send signal. CONSTITUTION:An output signal 21 of a priority encoder 2 is outputted to a selector 1 and fed back to AND gates 9-14 via a feedback circuit at the same time. When no request send signal of each terminal equipment exists, the input to the priority encoder 2 is all at '0' and since the output is all at '1', each AND gate is all opened through a 3-input AND gate 35. When a request send signal of a terminal equipment is confirmed, a corresponding data among input signals 22-27 is outputted as a data output signal 34, each AND gate is closed at the same time and the request send signal of other terminal equipments is not received until the reset of the corresponding flip-flop. Thus, it is prevented that a preceding request send signal is blocked by a succeeding call signal.
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