Which statement best describes static memory (SRAM) devices compared with dynamic memory (DRAM)?

Introduction / Context:
Static RAM (SRAM) and Dynamic RAM (DRAM) are the two fundamental types of semiconductor main memory. Understanding their retention behavior is critical for system design, performance, and power considerations.

Given Data / Assumptions:

• We are comparing SRAM vs. DRAM characteristics.
• Power is assumed to remain applied to the device.
• No magnetic or optical technologies are in scope.

Concept / Approach:
SRAM stores bits in bistable flip-flop circuits; as long as power is applied and noise margins are maintained, the data remains valid without refresh. DRAM stores bits as charge on capacitors that leak and must be periodically refreshed even when powered. Thus, the defining characteristic of SRAM is “no refresh required with power applied.”

Step-by-Step Solution:
Identify storage mechanism: SRAM uses cross-coupled inverters (flip-flops), DRAM uses capacitors.Analyze retention: SRAM holds state indefinitely with power; DRAM leaks and needs refresh.Conclude the correct description: data retained as long as power is applied; no refresh for SRAM.

Verification / Alternative check:
Device datasheets and textbooks list “no refresh” as a key SRAM advantage, offset by larger cell size and lower density compared to DRAM.

Why Other Options Are Wrong:
Magnetic/optical statements: not semiconductor main memory devices.Constant refresh with power applied: describes DRAM, not SRAM.

Common Pitfalls:
Assuming “static” means non-volatile without power; SRAM still loses data when power is removed. “Static” only means no refresh needed while powered.

Final Answer:
Semiconductor devices in which stored data is retained as long as power is applied (no refresh)