問61
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記憶素子として半導体メモリを用いているものはどれか。
平成24年度 秋期 ITパスポート試験 問61
テクノロジ系コンピュータ構成要素 › メモリ
This question's explanation and your answers so far.
解説
問 61
Incorrectア
A CD-ROM is an optical disc; its storage element is not a semiconductor but a resin disc. A laser beam is aimed at the pits (tiny depressions) formed on the disc, and the data is read from the strength of the reflected light — an optical recording method. It is read-only (Read Only Memory), and it does not use semiconductor memory as its storage element.
Incorrectイ
A DVD-RAM is an optical disc that can be rewritten repeatedly, but its storage element is still a disc-shaped medium. It uses phase-change recording, in which the heat of a laser beam switches the recording-layer material between a crystalline and an amorphous state; this is not semiconductor memory. Because the name contains RAM it is easily confused with semiconductor memory, but note that it is an optical disc all the same.
Incorrectウ
An MD (MiniDisc) is a magneto-optical disc (the same family as MO), a medium used mainly for recording music. To record, a laser heats the disc while a magnetic field is applied to change the direction of magnetization; to read, the change in the polarization of the reflected light is used. Its storage element is a disc coated with magnetic material, not semiconductor memory.
- エ
正解 The correct answer is エ, the USB Flash Drive. A USB flash drive uses flash memory as its storage element, that is, non-volatile memory built from semiconductors (integrated circuits). Data is written and erased electrically, and the contents are retained even when the power is turned off; it has no spinning disc mechanism and no laser read/write head at all. This point — an auxiliary storage device whose storage element is semiconductor memory — is what decisively sets it apart from the other three (optical discs / magneto-optical discs). SSDs and SD memory cards are in the same family, also using semiconductor memory (flash memory) as their storage medium.
ここがポイント
- Classifying storage media by recording method: semiconductor memory (USB flash drives, SSDs, SD cards = flash memory) / optical discs (CD, DVD, Blu-ray) / magneto-optical discs (MO, MD) / magnetic discs (hard disks). Tell them apart by which physical principle holds the data.
- Flash memory is non-volatile semiconductor memory that can be rewritten electrically, and its data is not lost when the power is turned off. Note that even when a name contains RAM, as with DVD-RAM, if the thing itself is an optical disc then it is not semiconductor memory.
用語