| 摘要 |
PURPOSE:To prevent an erroneous access from being generated by returning the flag of an LSI when an operating system is called directly and returning a flag in a memory when the system is called from a ledger file. CONSTITUTION:When a file is accessed by a normal operating system, the name of the file and a unit number are designated, the access routine of the operating system OS is called, and the insertion/extraction flag of an external storage medium FD 5 is read out of the LSI to check whether or not the external storage medium is inserted or extracted. Then when the medium is neither inserted nor extracted, file information in the memory 4 is used to read the medium 5 according to the information, but when the medium is inserted or extracted, the flag is saved in the memory 4 and the file information of the medium 5 is read. Further, when the ledger file is accessed, the filing name and a unit number are designated and a file access routine dedicated to the ledger file is called.
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