| 摘要 |
PURPOSE:To shorten lapse of time until starting of a system by providing a decision means that decides propriety of access of the first external storage device and a control means that selects and accesses the second external storage device based on decision of the decision means. CONSTITUTION:Before a hard disk 8 becomes ready, output of an AND circuit 9 is low, and output of an AND circuit 10 is high. In the case where it is decided by a comparator 3 that the access is to a track registered in a table on a back-up memory 1, access is made to a floppy disk 7 through a floppy control circuit 5. As time after power source for the floppy disk 7 is made on until it becomes ready is several seconds, quick starting process becomes possible. When a hard disk 8 becomes ready, output of the AND circuit 9 is made high by a ready signal 4 and output of the AND circuit 10 is made low by an inversion circuit 11, and changed to proper access of the hard disk 8.
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