令和2年度 ITパスポート試験問79

This question's explanation and your answers so far.

問79

頻出度★★☆

次の①～④のうち,電源供給が途絶えると記憶内容が消える揮発性のメモリだけを全て挙げたものはどれか。 ① DRAM ② ROM ③ SRAM ④ SSD

出典　令和2年度 ITパスポート試験問79

解説

問 79

Incorrectア
The combination “①, ②”. Although ① DRAM is correctly volatile, ② ROM is non-volatile memory whose contents remain even when the power is turned off, so it does not list only volatile memories and is therefore wrong.
イ
正解 Volatile memory is memory whose stored contents are lost when the power supply is cut off. Both ① DRAM and ③ SRAM are RAM (read/write memory used as main memory) and retain their contents only while powered, so they are volatile memory. Therefore the combination that lists only volatile memories is ① and ③, and the correct answer is “イ”, namely “①, ③”.
Incorrectウ
The combination “②, ④”. Both ② ROM and ④ SSD are non-volatile memory whose contents remain even when the power is turned off; they are not volatile memory, so this is wrong.
Incorrectエ
The combination “③, ④”. Although ③ SRAM is correctly volatile, ④ SSD is a non-volatile secondary storage device that uses flash memory, so it does not list only volatile memories and is therefore wrong.

ここがポイント

Volatile memory (contents lost when power is off) belongs to the RAM family, typified by DRAM (main memory) and SRAM (cache); non-volatile memory (contents kept when power is off) includes ROM and SSD (flash memory).
DRAM needs refreshing and is cheap with large capacity, while SRAM is fast and used as cache; the point tested here is that both are volatile.

用語

解答問79イ