Operands and Its Types in Machine Instructions

In simple words, an operand is a term used to describe any object that is capable of being manipulated. And  in computing, an operand is the part of a computer instruction which specifies what data is to be manipulated or operated on, while at the same time representing the data itself. The operand indicates where in registers or memory the data required for the operation is located. Some instructions do not require an operand, whereas some other instructions may require one, two, or three operands. For example, and add instruction requires two operands, and a not instruction requires only one.

  • Source operand
  • Result operand


Source operand : 

The operands that are inputs for the operation, is known as Source operand. The source operands contains the data or address of the data. Generally, the source operands data remains unaltered after the operation.

Result operand : 

he operation that may produce a result, is known as Result operand. The source operand is generally the destination, which contains data in a register or memory location.


Operand Types  :

Machine instructions operate on data. Data can be categorized as follows :

Addresses: 

It basically indicates the address of a memory location. Addresses are nothing but the unsigned integer, but treated in a special way to indicate the address of a memory location. Address arithmetic is somewhat different from normal arithmetic and it is related to machine architecture.


Numbers: 

All machine languages include numeric data types. Numeric data are classified into two broad categories: integer or fixed point and floating point.


Characters: 

A common form of data is text or character strings. Since computer works with bits, so characters are represented by a sequence of bits. The most commonly used coding scheme is ASCII (American Standard Code for Information Interchange) code.


Logical Data: 

Normally each word or other addressable unit (byte, half-word, and so on) is treated as a single unit of data. It is sometime useful to consider an n-bit unit as consisting of n 1-bit items of data, each item having the value 0 or 1. When data are viewed this way, they are considered to be logical data. Generally 1 is treated as true and 0 is treated as false.



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