Q5Microprocessor

Four key differences between Static RAM (SRAM) and Dynamic RAM (DRAM) are: (1) Storage mechanism — SRAM stores each bit in a bistable flip-flop circuit (typically 6 transistors per cell) that holds its state indefinitely as long as power is supplied, while DRAM stores each bit as an electrical charge on a tiny capacitor (typically just 1 transistor + 1 capacitor per cell), which naturally leaks away over time; (2) Refresh requirement — SRAM requires no periodic refreshing, since its flip-flop cells are inherently stable, while DRAM requires periodic refresh cycles (typically every few milliseconds) to recharge the leaking capacitors and prevent data loss, adding circuit complexity and periodically interrupting normal memory access; (3) Speed — SRAM is generally faster (lower access latency) than DRAM, since reading a stable flip-flop state is quicker than sensing and amplifying a small capacitor charge, and there is no refresh-cycle interruption to normal access timing; (4) Density and cost — DRAM achieves significantly higher storage density (more bits per unit chip area, since its 1-transistor-1-capacitor cell is much smaller than SRAM's 6-transistor cell) and correspondingly lower cost per bit, which is why DRAM is used for large main memory (where cost and density matter most) while SRAM, despite its higher per-bit cost, is used for smaller, speed-critical applications such as CPU cache memory.