| 摘要 |
PURPOSE:To attain long service life for battery power source, by providing a switching element between a signal line and a point having a prescribed level and controlling the conduction with a prescribed instruction for preventing unnecessary current, in an input circuit where a switch is connected to the input terminal directly. CONSTITUTION:In inputting data, an instruction setting an R-S flip-flop 10 is executed at first for turning on the switching element 13. When the switch 17 is opened in this case, a signal line 6 goes to a power supply voltage Vss level and when the switch 17 is closed, the signal line 6 goes to a power supply voltage VDD level with the resistance of the switching element 13. In executing the input instruction with this state, a control signal 11 goes to level 1, a gate 9 is conductive and an output of a buffer 7 is transmitted to a data bus 7. Through the end of execution of the input instruction, the gate 9 is interrupted, a flip- flop 14 is reset and the switching element 13 is turned off. Since the switching element 13 is turned on only the data input, no current flows via the switch 17. |
