問67
頻出度★★☆
フラッシュメモリの説明として, 適切なものはどれか。
平成29年度 秋期 ITパスポート試験 問67
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 67
Incorrectア
“Erasing data using ultraviolet light” describes an ultraviolet-erasable EPROM (UV-EPROM). It erases the entire chip by shining ultraviolet light through a window on top of the package, so its erasing mechanism differs from flash memory, which is rewritten electrically.
Incorrectイ
“Fast read speed, used as cache memory to bridge the performance gap between the CPU and main memory” describes SRAM (a fast, volatile memory). Flash memory is slower than SRAM and is not used for cache purposes.
- ウ
正解 “ウ” is correct. Flash memory is a semiconductor memory developed from EEPROM, and it can erase and rewrite data block by block all at once using electrical signals. It is also non-volatile, so data is not lost even after the power is turned off; for this reason it is widely used in USB flash drives, SD cards, SSDs, the built-in storage of smartphones, and other applications where data must be kept after power-off. The description “It is an electrically rewritable, non-volatile memory” exactly captures this characteristic.
Incorrectエ
“Requires refresh operations and is often used as main memory” describes DRAM. DRAM holds data with the electric charge in capacitors, so it is a volatile memory that needs periodic refreshing; it is a different thing from flash memory, which needs no refresh and is non-volatile.
ここがポイント
- Flash memory = a non-volatile memory that can be erased all at once and rewritten electrically (a kind of EEPROM), used in USB flash drives, SD cards, SSDs, and so on.
- Distinguishing semiconductor memories: SRAM (fast, for cache) and DRAM (needs refresh, for main memory) are volatile, while UV-EPROM is erased by ultraviolet light. Identify them by whether they are volatile or non-volatile and by their erasing method.
用語