| 摘要 |
PURPOSE:To eliminate a overhead at key check by executing automatically access control by a virtual computer, at the time of accessing to a virtual computer area in case a virtual computer controlling monitor program of a real computer is being executed. CONSTITUTION:A tag register 30 has a tag bit corresponding to each general register, and a necessary bit is set in advance by a virtual computer controlling monitor program (VM monitor) 3 of a real computer. At the time of execution of the VM monitor 3, usually '0' is outputted as an access key to a control line 11, but when it is detected that the general register which is designated by the tag register 30 is designated by an address register designating part 19 for instruction, an access detecting part 31 switches the access key 7 of PSW5 of a virtual computer so as to use as an access key and outputs it. Accordingly, access control of the virtual computer is executed automatically, and it is made unnecessary that the VM monitor 3 executes a key check at every access.
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