問82
頻出度★☆☆
PC に接続された周辺機器を, アプリケーションプログラムから利用するために必要なものはどれか。
平成25年度 秋期 ITパスポート試験 問82
テクノロジ系コンピュータ構成要素 › 入出力デバイス
This question's explanation and your answers so far.
解説
問 82
Incorrectア
A compiler is a language processing program that translates a source program written in a high-level language such as C or Java, all at once, into machine language (an object program) that the computer can execute directly. It is used at the stage of developing a program and turning it into an executable form, and it has no function for controlling peripheral devices connected to a PC. A compiler is never needed at the moment when an already completed application uses a peripheral device.
- イ
正解 The correct answer is イ, the device driver. A device driver is dedicated software for controlling peripheral devices such as printers, mice, and external disks; it is installed into the OS and used from there. Because the control procedures and signal exchanges differ from product to product, if application programs tried to operate the hardware directly, a separate program would be needed for every model. Instead, the device-specific control is handled by the device driver, and the application only has to call a common command provided by the OS (for example, “print”). The OS passes that command to the device driver for the relevant device, and the driver actually operates the hardware. Thanks to this arrangement, an application can use a peripheral device without being aware of which model is connected. Conversely, a peripheral device for which no matching device driver has been installed cannot be used from applications even if it is physically connected to the PC. Therefore, what is required in order to use a peripheral device from an application program is the device driver.
Incorrectウ
Plug and Play is a function whereby, when a peripheral device is connected to a PC, the OS automatically recognizes the device and, on the user's behalf, automatically installs and configures the necessary device driver. It is merely a mechanism that reduces the labor of installing and configuring device drivers; Plug and Play itself does not control the device. What it prepares automatically is, after all, still a device driver, and even in an environment without this function the peripheral device can be used as long as the user installs the driver manually. Therefore, the thing that is indispensable for use is the driver.
Incorrectエ
Hot plug (hot swap) is a function that allows peripheral devices to be plugged in and unplugged while the PC remains powered on, and it is adopted for USB devices and the like. It is no more than a function concerning the method of connection, namely that devices can be attached and detached without turning off the power, and it does not solve the problem of how a connected device is controlled from an application. Even a device that must be connected only after the power is turned off can be used from an application as long as a matching device driver exists.
ここがポイント
- A device driver is device-specific software for controlling a peripheral device, installed into the OS and used from there. An application only has to call the common interface provided by the OS, and the differences in control procedures between models are absorbed by the device driver. Without a matching device driver, a peripheral device that has merely been connected cannot be used from applications.
- Distinguish the terms related to connecting peripheral devices: Plug and Play is a function in which the OS automatically recognizes a connected device and even automates the installation and configuration of its driver, while hot plug (hot swap) is a function that allows devices to be plugged in and unplugged with the power on. Both are mechanisms that improve convenience, and neither can take the place of the device driver that actually controls the device. A compiler is a language processing program that translates a high-level language into machine language and has nothing to do with controlling peripheral devices.
用語