| 摘要 |
PURPOSE:To realize input/output protection by checking whether or not a privileged processing request is effective in an interruption processing routine when the privileged processing request is generated and a primary storage means is set. CONSTITUTION:A flip-flop 19 indicates a privileged processing request flag and a register 22 is inhibited from being accessed except in an interruption processing routine wherein the flag is not set. On the other hand, when the privileged processing request is generated and the flip-flop 19 is set, a return address is checked in the interruption processing routine to check whether or not the privileged processing request is effective. When not, this is canceled to realize the input/output protection. Consequently, a protection mechanism is realized which is never reset by an application program.
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