What Is Control Word? Give the Structure of a Control Word.

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Detailed Solution

A control word is a binary or coded instruction used in computer architecture to control the operations of a CPU or microprocessor.

In digital systems and microprocessors, the control unit directs the flow of data and operations using control signals. These signals are grouped into a single binary pattern known as a control word. It determines how the processor performs an instruction such as addition, subtraction, or data transfer.

Structure of a Control Word

The structure of a control word varies by system, but it generally includes several fields representing operations and data paths.

Field	Purpose
Opcode Field	Specifies the operation (like ADD, SUB, MOVE)
Source Register Field	Indicates the source of data
Destination Register Field	Specifies where the result will be stored
Control Flags	Enable or disable specific CPU functions
Mode Bits	Define addressing or data transfer mode

Example

In an 8-bit processor, a control word may look like this:

0101 1010

Here each bit represents a specific control signal such as memory read, write, or ALU operation.

Uses