| 摘要 |
A telephone system with central processor control has telephones including respective data circuits. Each data circuit scans a respective keypad and stored data relating to the state of the keys thereon. The stored data is forwarded to the central processor on demand from the processor. The data circuit scans the keys of the keypad and then scans a data input connected to the central processor. On detection of a prefix pulse from the central processor the data circuit makes repeated samples of this data input until detection of a start pulse. Once the start pulse has been detected the data circuit scans the data input at the bit rate. If a key of the keypad changes state more than once between each demand from the processor, the respective data relating to the subsequent change is not modified by the data circuit. |
