| 摘要 |
<p>PURPOSE:To realize a simple and inexpensive power save function by adding a reset control circuit for receiving a reset control signal through a control port from a CPU and setting a reset signal supplied to a co-processor to an effective/ineffective state. CONSTITUTION:In the case a co-processor 2 is unnecessary, a CPU 1 makes a chip select signal supplied to the co-processor 2 through a control port 3 ineffective, and also, makes a reset control signal to the co-processor 2 effective. Also, in the case the co-processor 2 is necessary, the reset signal is made ineffective, and the chip select signal is made effective. Subsequently, when the received control signal becomes effective by a reset control circuit 8, the reset signal to the co-processor 2 is made effective immediately, and when the reset control signal becomes ineffective, the reset signal to the co-processor 2 is made ineffective by synchronizing with an internal clock signal of the CPU 1. In such a way, power save of the co-processor 2 can be realized without using a signal cut-off circuit, or without stopping temporarily an operation of the CPU 1.</p> |
