問56
頻出度★☆☆
PCのOSに関する記述のうち, 適切なものはどれか。
平成22年度 春期 ITパスポート試験 問56
テクノロジ系ソフトウェア › オペレーティングシステム
This question's explanation and your answers so far.
解説
問 56
Incorrectア
Incorrect. The interface between the OS and applications is called the API (system calls), but its specification differs from one OS to another. That is why an executable file built for Windows does not run as is on macOS or Linux, and why developers must write programs with the target OS in mind. Saying that the interface is unified contradicts the facts.
- イ
正解 The correct answer is イ. The most central role of an OS (Operating System, or basic software) is “resource management.” The CPU processing time a PC has, the areas of main memory, auxiliary storage devices such as hard disks and SSDs, and peripherals such as printers and the network are all limited shared resources, and if several application programs competed for them at will at the same time, they would conflict. The OS therefore acts as an intermediary, controlling and allocating them: how much CPU time to give to which program (task management and scheduling), which area of memory it may use (memory management), and how files are read and written (file management). This statement matches the definition of an OS exactly, so it is appropriate.
Incorrectウ
Incorrect. The OS treats the contents of a file as a mere sequence of bytes, and it does not have as a standard feature the ability to detect and convert the character encoding (Shift_JIS, UTF-8, and so on) automatically. Interpreting the character encoding is the responsibility of the application, and specifying it wrongly produces garbled text. So the statement that an application need not be aware of this does not hold.
Incorrectエ
Incorrect. There is no obligation to disclose source code. Windows and macOS are representative commercial operating systems whose source code remains undisclosed, and even so, applications can use the OS’s functions as long as the published API specifications are available. It is open-source operating systems such as Linux that release their source code, and that is merely a licensing policy the developers chose, not an obligation.
ここがポイント
- The three main functions of an OS are resource management (allocating the CPU, memory, auxiliary storage, and peripherals), abstraction of the hardware, and provision of a user interface. In particular, allocating limited resources fairly and efficiently among multiple applications is the very reason an OS exists.
- Applications call OS functions through the API (system calls), but because the API specification differs from OS to OS, there is no compatibility between them. Keep in mind as well that converting character encodings is the responsibility of the application, and that no obligation to disclose the OS source code exists either.
用語