問66
頻出度★☆☆
PC の起動時に動作するプログラムの種類を BIOS (Basic Input Output System), OS, 常駐アプリケーションプログラムの三つに大別した場合, これらのプログラムを実行される順に並べたものはどれか。
平成25年度 春期 ITパスポート試験 問66
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 66
- ア
正解 The correct answer is ア (BIOS → OS → resident application programs). When a PC is powered on, the BIOS stored in ROM or flash memory runs first. The BIOS initializes the hardware and performs a self-test (POST), making minimal input/output such as the keyboard and disks usable, and then reads the boot program from the boot disk and loads the OS into main memory. Next the OS starts up and builds the execution environment that application software needs, including memory management, the file system, and device drivers. Resident application programs (antivirus software, resident input-assist tools, and the like) are application software that is started automatically under the control of the OS, so they are loaded after the OS has come up. In other words, control is passed upward starting from the layer closest to the hardware, so the order BIOS, OS, resident application programs is correct.
Incorrectイ
The error is placing the OS before the BIOS. The OS is stored on auxiliary storage such as a hard disk or SSD, and reading it out and loading it into main memory is the role of the BIOS. The OS cannot run before the BIOS runs.
Incorrectウ
The error is placing the BIOS last. The BIOS is the startup program that is executed first, right after power-on; it never starts after the OS and resident applications have already run. Beginning the sequence with the OS is also wrong, for the same reason as in イ.
Incorrectエ
The error is placing resident application programs first. A resident application is application software that runs under the control of the OS, so it cannot execute at a stage where the OS has not yet started, nor can it run before the BIOS.
ここがポイント
- The PC startup order is BIOS (hardware initialization, POST, loading the OS) → OS (building the execution environment) → resident application programs (application software started automatically on top of the OS); control is handed over layer by layer, starting from the layer closest to the hardware.
- Grasp this division of roles: because the BIOS resides in ROM/flash memory, it can run immediately after power-on, and it serves as the entry point of startup that reads the OS — which sits on auxiliary storage — into main memory.
用語