What does a 2-to-4 decoder do in the datapath?

What does a 2-to-4 decoder do in the datapath?

• A. It selects which register to load based on a 2-bit address
• B. It mediates between clock phases
• C. It enforces parity on the data
• D. It stores the 2-bit address in a register

Answer: (A)

A 2-to-4 decoder translates a 2-bit address into four one-hot enable signals. For each possible pair of input bits, exactly one of the four outputs goes high, enabling a specific path or device. In the datapath, those four outputs can drive the load enables of four registers, so the register corresponding to the 2-bit address is the one that gets loaded. This is exactly how a compact address selects a single destination without ambiguity. It doesn’t deal with clock timing, parity checking, or storing the address—it simply converts the binary address into a unique enable signal for the chosen register.

A 2-to-4 decoder translates a 2-bit address into four one-hot enable signals. For each possible pair of input bits, exactly one of the four outputs goes high, enabling a specific path or device. In the datapath, those four outputs can drive the load enables of four registers, so the register corresponding to the 2-bit address is the one that gets loaded. This is exactly how a compact address selects a single destination without ambiguity. It doesn’t deal with clock timing, parity checking, or storing the address—it simply converts the binary address into a unique enable signal for the chosen register.