With regard to computer memory, which of the following statement(s) is/are…
2020
With regard to computer memory, which of the following statement(s) is/are TRUE?
(A) Cache memory is 'volatile' memory.
(B) Magnetic memory is 'volatile' memory.
(C) Flash memory is 'volatile' memory.
(D) RAM is 'volatile' memory.
Choose the correct answer from the options given below:
- A.
(A) and (B) only
- B.
(D) only
- C.
(A) and (D) only
- D.
(C) and (D) only
Attempted by 11 students.
Show answer & explanation
Correct answer: C
Concept
Memory is classified as volatile or non-volatile by what happens when power is removed. Volatile memory loses its stored contents the moment power is cut off; non-volatile memory keeps its contents without any power. Whether a technology is volatile depends on its physical storage mechanism - not on how fast it is or where it sits in the memory hierarchy.
Applying it to each memory type
Memory | Storage mechanism | Keeps data without power? | Volatile? |
|---|---|---|---|
Cache | SRAM - transistor flip-flop cells that need power to hold state | No | Yes |
Magnetic (HDD, tape) | Magnetised regions on a physical surface | Yes | No |
Flash | Electrons trapped in floating-gate cells | Yes | No |
RAM (DRAM) | Charge on tiny capacitors that must be powered and refreshed | No | Yes |
Result
Cache and RAM both rely on powered transistor or capacitor cells, so they lose their contents when power is removed - both are volatile. Magnetic storage and flash store data physically (magnetisation and trapped charge respectively) and keep it without power, so both are non-volatile. The only true statements are therefore that cache is volatile and that RAM is volatile; magnetic memory and flash being called volatile are both false.
Cross-check
Sanity check: anything you can switch off and still find your files on afterwards - a hard disk, a USB or SSD flash drive - must be non-volatile, which rules out magnetic and flash being volatile. Anything wiped on a reboot, such as the live working contents of RAM and cache, is volatile.