GATE CS 2002 Q2.7 — ALU, Data-path and Control Unit

In Horizontal Microprogramming, control signals are represented in an unencoded format:

• No Decoders Required: Since each control signal is directly controlled by a dedicated bit in the microinstruction, there is no need for decoding logic (signal decoders). This makes execution faster. Thus, statement (A) is correct.
• Larger Microinstruction Size: Because every control signal has its own bit, the width of the microinstruction is significantly larger compared to vertical microprogramming (where signals are encoded to save space). Thus, statement (B) is correct.
• One Bit per Control Signal: By definition, horizontal microprogramming allocates one bit to each independent control signal. Thus, statement (C) is correct.

Since all three individual statements are correct, the correct option is D.