On the subject of real-time OS's, I read this sentence:


Where 不可 apparently means "to mask". I can understand that "割り込み masks something", but I can't understand "不可とする"

The definition of 不可 that I looked up was "wrong, bad, improper, inadvisable". So, what does "不可とする" mean in this context?

  • 1
    means "not". means "possible/available".
    – Teno
    Sep 28, 2012 at 22:16

2 Answers 2


I think that the sentence means “It disables (masks) interrupts temporarily,” although I am not sure if I understand the author’s intent of the parenthesized part “(マスク)” in the original sentence correctly.

不可 here means “disabled.” I would like to add that this usage is not common. The usual word for “disabled” is 無効, and the sentence is more usually written as 割り込みを一時的に無効にする, ignoring the parenthesized part.

In addition, I think that the use of parentheses in the given sentence is nonstandard. The use indicates that マスク is either an explanation or a paraphrase of 不可, but explaining 不可 as “mask” or “masking” is, well, a type error. I think that what the author wanted to say is something like

割り込みを一時的に無効にする (マスクする)。

where マスクする (to mask) is another way of stating 無効にする (to disable).


"I can understand that '割り込み masks something'".

The word 割り込み means a CPU interrupt. So it appears to say "Temporarily disable (via bit masking) interrupts".

The 不可 means "improper, inadvisable", as you said. But the とする means "to make such". So altogether 不可とする means disable.

  • So then "disable" would be appropriate?
    – Chris
    Sep 28, 2012 at 17:51
  • Yea. I edited it to expound on that. Sep 28, 2012 at 18:05

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