NIMCET 2009 — Computer PYQ

In computer architecture, the Control Unit ($CU$) can be implemented in two primary ways: Hard-wired and Micro-programmed.

• Speed: A Hard-wired Control Unit uses combinational circuits and hardware logic, making it significantly faster because there are no memory lookups involved. In contrast, a Micro-programmed Control Unit must fetch micro-instructions from a control memory ($ROM$), which introduces a delay. Therefore, it is slower than a hard-wired unit.

• Flexibility: The main advantage of a Micro-programmed design is its flexibility. Since the control signals are stored as software (micro-code) in memory, it is much easier to modify or facilitate the implementation of new instructions by simply updating the micro-code rather than redesigning the physical hardware.

Since both statements (b) and (c) are correct characteristics of a micro-programmed control unit, the final answer is (d).