| 摘要 |
PURPOSE:To connect many circuits to one terminal of one sound source unlimitedly and to reduce the number of terminals of a switchboard body by providing a counter which controls the start and stop of a talkie device. CONSTITUTION:If a subscriber S1 is connected to the talkie device TKE, a start order is sent out not unconditionally, but only when the contents of a start/ stop control counter SPCNT change from ''0'' to ''1'' by adding ''1'' to the initial value of the start/stop control counter SPCNT. If the subscriber is disconnected, a stop order is sent out only when the contents change from ''1'' to ''0'' by subtracting ''1'' therefrom. Other subscribers S2 and S3 are controlled similarly. Namely, when the connection of one subscriber is made, the start/stop control counter SPCNT counts up by addition, and when the subscriber is disconnected, the counter SPCNT counts down by subtraction; and the counter SPCNT goes down to ''0'' after the final subscriber is disconnected and the stop order is sent out, so multiple access to the talkie device TKE is attained without paying attention to a simultaneous connection on the side of the talkie device TKE. |
