Q. Explain about Variable-Length of Instructions?

With the better understanding of computer instruction sets designers developed the idea of having a range of instruction formats of different length. What could be benefits of such a set? The benefits of this scheme are:

• Large number of operations can be offeredthat have different lengths of instructions.
• Flexibility in addressing scheme can be offered compactly andefficiently.

But the fundamentalshortcoming of such a scheme is to have a complex CPU.

A significant feature about these variables length instructions is: The CPU is not aware about length of next instruction that is to be fetched. This problem can be controlled if every instruction fetch is made equal to size of the longest instruction. So sometimes in a single fetch multiple instructions can be fetched.