問88
頻出度★☆☆
PCと周辺機器などを無線で接続するインタフェースの規格はどれか。
平成23年度 秋期 ITパスポート試験 問88
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 88
- ア
正解 The correct answer is ア. Bluetooth is a short-range wireless communication standard that connects devices such as PCs and smartphones to their peripheral devices by radio waves. It uses radio waves in the 2.4 GHz band (the ISM band), which can be used without a licence, and although the communication distance is short — only a few metres to about 10 m — in exchange it consumes little power and suits small devices that run on batteries for a long time. Because it uses radio waves, there is no need to join the devices with a cord the way a USB cable does, and unlike infrared communication (IrDA) it can communicate even when there are some obstacles between the devices and even when they are not facing each other. Typical real uses are wireless mice and wireless keyboards, headsets and speakers, printers, and data transfer to and from mobile phones and smartphones — exactly the “interface that connects a PC and peripheral devices wirelessly” that the question refers to. To use it, you first perform an operation called pairing, in which the devices to be connected are registered with each other; after that the pair connects automatically. Judging this question needs only the single point of “wireless or wired”: イ and エ are wired cable connections and ウ is an expansion bus inside the PC itself, so the only wireless connection standard is ア.
Incorrectイ
IEEE 1394, also called FireWire or i.LINK, is a wired serial interface standard that connects devices with a dedicated cable. It is used for peripheral devices that transfer large amounts of data at high speed, such as digital video cameras and external hard disks, and its features include hot plugging, which lets devices be plugged in and out with the power still on, and daisy-chain connection, in which devices are linked one after another. It is indeed an interface for connecting external peripheral devices, but a cable is essential for the connection and no radio waves are used, so it does not satisfy the question's condition of being wireless.
Incorrectウ
PCI (Peripheral Component Interconnect) is an internal bus standard for fitting expansion cards such as graphics boards and LAN boards into expansion slots on the motherboard inside the PC itself. It is an internal pathway that exchanges data between the CPU or memory and the expansion cards, and it is not in the first place an interface for connecting external peripheral devices by cable or by radio waves. It is not wireless, and what it connects is different as well, so it is wrong.
Incorrectエ
USB 2.0 is the most widely used wired serial interface standard for connecting a PC and peripheral devices, and the connection is made with a USB cable. It has a High-Speed mode with a maximum transfer rate of 480 Mbit/s, and its features include being able to connect many devices in a tree shape using hubs, supporting hot plugging, and offering bus power, which supplies electricity to peripheral devices over the cable. It fits the question in that it is a standard for connecting peripheral devices, but its means of connection is ultimately a cable and not wireless, so it is wrong.
ここがポイント
- Definition of Bluetooth — a standard that wirelessly connects a PC and peripheral devices (mice, keyboards, headsets, smartphones, and so on) over a short range of a few metres to about 10 m using radio waves in the 2.4 GHz band. It has low power consumption, can communicate even when obstacles are present, and registers the devices with each other by pairing when you begin using it. Remember Bluetooth as the wireless peripheral interface.
- Contrast with wired interfaces — USB (cable connection, up to 127 devices in a tree shape, hot plugging and bus power) and IEEE 1394 (FireWire / i.LINK, cable connection, aimed at video equipment) are both wired external interfaces. PCI is an internal bus standard that connects expansion cards inside the PC itself, and it is not for external connection. It is a good idea to organise these along the two axes of wireless versus wired and external versus internal.
用語