Question

Which of the following is a key reason for choosing DRAM over SRAM for main memory?

• A. DRAM requires fewer transistors per bit than SRAM
• B. DRAM is faster than SRAM
• C. DRAM consumes less power than SRAM
• D. DRAM is non-volatile, unlike SRAM

Hint:

A DRAM cell is one transistor plus a capacitor, giving higher density than SRAM's six-transistor cell.

Answer 1

The Correct Option is A

Step 1: The choice of memory for a large main store comes down to cost and density per bit.

Step 2: SRAM builds each bit from a six-transistor flip-flop, which is bulky. DRAM builds each bit from just one transistor plus a capacitor, so its cells are tiny.

Step 3: Fewer transistors per bit means DRAM packs far more capacity onto a chip at lower cost, which is exactly why it is used for the bulk of main memory.

Step 4: The other claims fail: DRAM is slower than SRAM, it needs periodic refresh so it is not clearly lower power, and it is volatile just like SRAM. Only the fewer-transistors reason holds.

\[\boxed{\text{DRAM requires fewer transistors per bit than SRAM}}\]