| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that a peak current and an unwanted radiation noise increases when an address is changed and that a circuit which is not accessed is actually decoded to increase a consumption current because an access operation takes place in all of a plurality of peripheral circuits in a conventional accessing method. SOLUTION: A special access effective signal that is exclusively provided is used, a register group is accessed with a direct register designation, and a normal address decoding operation is stopped at the same time or an address bus output is stopped in the case of accessing the register group to which accesses are frequently made when the register group is actually used. Thus, address decoding itself is not performed, the consumption current and the peak current are suppressed, and the effects of power saving and low unwanted radiation noise are obtained.
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