A register is made of which devices?

A register is made of which devices?

• A. D flip-flops
• B. T flip-flops
• C. JK flip-flops
• D. RS flip-flops

Answer: (A)

A register uses a storage element for each bit, and the easiest, most predictable choice for that element is the D flip-flop. On a clock edge, the D input value is captured and held on Q, so each bit of the register can be loaded in parallel from a data bus. A register is simply many D flip-flops connected in parallel with a common clock, each storing one bit of the word. Other flip-flop types introduce extra behavior—T toggles, JK can toggle or require gating to avoid unintended changes, and RS has a forbidden state when both inputs are active—so they would need additional logic to behave like a stable storage element. That extra complexity is why D flip-flops are the standard building blocks for registers.

A register uses a storage element for each bit, and the easiest, most predictable choice for that element is the D flip-flop. On a clock edge, the D input value is captured and held on Q, so each bit of the register can be loaded in parallel from a data bus. A register is simply many D flip-flops connected in parallel with a common clock, each storing one bit of the word.

Other flip-flop types introduce extra behavior—T toggles, JK can toggle or require gating to avoid unintended changes, and RS has a forbidden state when both inputs are active—so they would need additional logic to behave like a stable storage element. That extra complexity is why D flip-flops are the standard building blocks for registers.