計算機概論 - 虛擬記憶體計算 - 考試

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.

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題目(二): An operating system uses virtual memory but requires the whole
program to be in physical memory during execution (no paging or
segmentation). The size of physical memory is 100 MB.
The size of virtual memory is 1 GB.

Q5: How many programs of size 10 MB can be run concurrently by this
operating system?
My answer -> Since programs have to be in physical memory during execution,
then 100 MB/10 MB = 10 programs can be run concurrently by this
operating system.

Q6: How many of them can be in memory at any time?
My answer -> 100 MB / 10 MB = 10 programs can be in memory at any time.

Q7: How many of them must be on disk?
My answer -> 10 programs are in physical memory, and the size of virtual
memory is 1024 MB, which means 102 programs can be stored in
disk + physical memory. So 102-10 = 92 programs must be on disk.

需要大家幫忙糾正錯誤，謝謝。

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