| 摘要 |
PURPOSE:To increase a transmission speed and also to decrease the number of parts, by constituting a key telephone system using a microcomputer, so that the microcomputer is used for controlling the write of a transmission data and the read of a receiving data, and this computer is not used when transmitting and receiving a data. CONSTITUTION:When a data is transmitted to telephone sets TELm(m denotes 1-m) from a main equipment side containing a data transmitting and receiving circuit DTR, a switching circuit SW, and a computer CC, a data to be transmitted is received from the computer CC and is held in a data transmitting shift register SR1. When transmission of the data is started, a stepping pulse to the shift register SR1 is counted by a counter COU1. When the stepping pulse of all bit portion of a data to be transmitted by the counter COU1 has been completed, stepping of the shift register 1 is stopped. At the same time, a data receiving shift register SR2 is made a steppable state so that a data from the telephone sets TELm can be received. |
