| 摘要 |
<p>PURPOSE:To keep the normal processing speed of an electronic computer system by switching the clock to be applied to a CPU to a clock of a lower frequency in order to reduce the power consumption in a keyboard input waiting state and at the same time detecting the using state of the system by means of hardware. CONSTITUTION:A key code storage circuit 2 stores temporarily the key codes inputted through a keyboard 3. A flag register 4 outputs a status signal 10 based on the presence or absence of a key code in the circuit 2. A counter circuit 5 starts its counting operation when the signal 10 shows the absence of an unprocessed key code. Then the circuit 5 outputs a clock selection control signal 11 to a clock frequency selector 6 after a fixed period. The selector 6 switches the frequency of the clock which is supplied to a CPU 1.</p> |
