在計算機概論課本上看到的兩題練習題，不過是英文的，所以我也用英文回答。
我對這些東西不是很了解，怕翻成中文以後會翻錯，所以直接貼原文上來，保險一點。
題目(一)：;A multiprogramming operating system uses paging.
The available memory is 60 MB divided into 15 frames, each of 4 MB.
Program A needs 13 MB. Program B needs 12 MB. Program C needs 27 MB.
Q1: How many frames are used by program A, B and C?
My answer -> Program A use 4 frames, program B use 3 frames,
and program C use 7 frames.
Q2: How many frames are unused?
My answer -> 15-(4+3+7) = 1. So 1 frame is unused.
Q3: What is the total memory wasted?
My answer -> 60 - (13+12+27) = 8. So 8 MB of memory is wasted.
Q4: What percentage of memory is wasted?
My answer -> 8/60 = 13.3% (approximately). So 13.3% of memory is wasted.

故意不寫答案嗎？ XDQ2, Q3 我不會把沒用的那個 frame 當 waste, 因為它之後有需要還是可以被用。所以應該是4MB, 浪費率4/56Q5 我覺得題意不清，應該要看這OS 支不支援 thread和 multi-core其實整個題目二陷阱很多，處理 switching 的程式要不要占記憶體？當然要！那就不可能把100MB memory塞滿你的程式。大學教科書這種要思辨的問題，還是去專版問吧

好的，實在太感謝你了。