INSTRUCTION SET DESIGN

INSTRUCTION SET DESIGN

A computer must be able to perform all the computable functions. For this it uses different types of instructions, which are collectively called as instruction set

Instruction set design is the most interesting, analyzed aspect of computer design. It affects many aspects of the computer system and is a tough task, so it must designed very carefully.

The following are the most important fundamental design issues in instruction design.

(i) Operation Repertoire : This issue is concerned with how many and which operations are to be provided, and how complex operations should be

(ii) Data Types : This issue deals with the various types of data upon which operations are performed.

(iii) Instruction Format : This issue is concerned with instruction length (in bits), number of addresses, size of various fields and so on.

(iv) Registers : This is concerned with the number of registers that can be referenced by instructions, and their use.

(v Addressing: This issue is concerned with the mode or modes by which the address of an operand is specified.

These fundamental issues are interrelated with each other and so they must be considered together while designing an instruction set.