| 摘要 |
PURPOSE:To discriminate not only a key end but also a key input end by a simple circuit configuration, by detecting a key end of other key, too, after an interruption signal has been generated, so that it is discriminated that all the key inputs have ended. CONSTITUTION:When an electric power supply is turned on, as for this counter 1, signals D0-D3 obtained by each output A-D of the counter 1 for counting a system clock signal of a signal line 1a through a 3 state buffer 2 are sent out to a data bus DB through a buffer 3 controlled by a read address select signal, are inputted to a central processor (CPU), and are data-processed. Also, the signals D0-D3 from the counter 1 are decoded by a decoder 4, and at every counting of the counter 1, a select signal is generated onto 10 signal lines S0-S9. |
