| 摘要 |
PROBLEM TO BE SOLVED: To provide a game machine that can eliminate a defect that memory data of random access memory is destroyed, because of decrease and fluctuations of a power supply, and a backup power source can protect the random access memory. SOLUTION: Access control register is provided in RAM 222, and decides whether there is an access to RAM 222 or not according to value of designated bit. Rewriting of the bit is conducted while an operation of CPU 221 is still stable in response to non-mask able cutting-in, or the like that generates backup power source when power cut occurs instantaneously. When the value of the bit shows that there is no access, neither of a readout and a data entry from RAM 222 can be conducted. It can prevent destruction of memory data due to an abnormal access to RAM 222 because a CPU action becomes unstable in case of an instantaneous power cut.
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