Question

What must an instruction specify?

(computer organization and design)

1.

2.

3.

4.

Answer 1

Given, What must an instruction specify?

Answer: An instruction specify these 4 things:

1. operation to perform

=> Operation here is declared or known as operand in any instruction. An operand is the predefined instruction for each and every microprocessor or to be known as operation.

Example: Add ax, bx

2. operands and from where to find and fetch

=> Operands are called the variables or an object space from where we reference the value. In most of cases we use different addressing mechanism like register or direct addressing,

Example: Mov ax, 08H

3. result store, if it has/generate one

=> Result here is referenced to the area or storage memory which will hold the result. In most of the case the result is stored by the higher memory or double memory space than the operands one.

Example: Mul ax, 07H

Here, ax has some value and we need to multiply 07 to it and requires more space to store so ax provides more space than any other common registers.

4. Next instruction to look for

=> This statement is not always true or required since only some instruction support such specification of presenting next instruction address. For those who don't get the next instruction using PC(Program Counter).

Example: JMP 6200H

All these 4 are necessary type for an instruction to properly execute.

Please let me know in the comments if you need more help in this.