問60
頻出度★★☆
コンピュータの記憶階層におけるキャッシュメモリ, 主記憶及び補助記憶と, それぞれに用いられる記憶装置の組合せとして, 適切なものはどれか。
キャッシュメモリ 主記憶 補助記憶 ア DRAM HDD DVD キャッシュメモリ 主記憶 補助記憶 イ DRAM SSD SRAM キャッシュメモリ 主記憶 補助記憶 ウ SRAM DRAM SSD キャッシュメモリ 主記憶 補助記憶 エ SRAM HDD DRAM
令和元年度 秋期 ITパスポート試験 問60
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 60
Incorrectア
The error is assigning DRAM to cache memory. Cache should use SRAM, which is faster than DRAM. It also lists HDD as main memory, but HDD is a device used for secondary storage and belongs to a different layer than main memory (DRAM).
Incorrectイ
The error is assigning SRAM to secondary storage. SRAM is volatile memory that loses its contents when the power is turned off; it is high-speed memory meant for cache and cannot be used for secondary storage, which requires non-volatility. Placing DRAM in cache is also inappropriate.
- ウ
正解 In a memory hierarchy, the closer to the CPU, the faster, smaller in capacity, and more expensive the storage becomes. Cache memory uses SRAM, the fastest type (static RAM that needs no refresh to retain data); main memory uses DRAM (dynamic RAM), which is slower than SRAM but cheaper and easier to make in large capacities; and secondary storage uses SSD, which is non-volatile and keeps its contents even when the power is turned off. Option ウ’s “SRAM／DRAM／SSD” correctly matches this hierarchy, so ウ is appropriate.
Incorrectエ
Cache memory = SRAM is correct, but assigning HDD to main memory and DRAM to secondary storage reverses the two and is wrong. DRAM is volatile memory for main memory and cannot serve as secondary storage, while HDD is a device for secondary storage and cannot serve as main memory.
ここがポイント
- Memory hierarchy by speed: cache memory (SRAM) > main memory (DRAM) > secondary storage (HDD/SSD/DVD). The higher the level, the faster, smaller, and more expensive it is.
- SRAM needs no refresh and is fast, making it suitable for cache; DRAM is cheap and high-capacity, making it suitable for main memory. Both are volatile, so secondary storage, which needs non-volatility, uses SSD/HDD/DVD.
用語