| 摘要 |
<p>PURPOSE:To omit an input terminal for switching a clock frequency, and to decrease the number of input terminals, by using a signal output terminal and a signal input terminal both for other processing operation and switching the clock frequency. CONSTITUTION:A switching operation for an input clock frequency is executed by switching a changeover switch SW in accordance with frequency 50/60Hz of an external input clock (50Hz when closing), connecting this changeover switch SW between a signal output terminal D0 and a memory read input terminal MR.IN being a signal, which are used for other processing operation, respectively, and monitoring whether a detection signal exists in said input terminal MR. IN or not, when the detection signal has been sent out from said output terminal D0 in the course of power-on, resetting and initializing. When a normal signal is being outputted from the output terminal D0 in the course of the main processing operation, an input monitoring operation of the input terminal is inhibited.</p> |
