1. Introduction
Microprocessors are the central processing units (CPUs) fabricated on a
single integrated circuit (IC). OR The microprocessor is the “brain” of a
computer system: it fetches instructions, decodes them, executes them,
and coordinates data movement.They execute instructions, perform
arithmetic and logic operations, and control system components through
timing and signals.
The evolution of Intel microprocessors represents the historical
progression of computing hardware, from simple 4-bit devices to today’s
powerful multi-core architectures. Each new generation improved upon
the previous in terms of speed, architecture, instruction set, and
integration.
According to Barry B. Brey and M. Morris Mano, this evolution is not
only technological but also architectural, it demonstrates how hardware
design adapts to new computing requirements while maintaining
backward compatibility through the x86 family.
2. Functions of Microprocessor:
2.1 Fetching Instructions
The processor retrieves instructions from memory using the address bus
and stores them in the instruction register for processing.
Example: Fetching the “add” command in a calculator app.
2.2 Decoding Instructions
The control unit interprets the fetched instruction to determine the
operation type (arithmetic, logic, or data transfer).
Example: Decoding ADD A, B means adding contents of register B to A.
2.3 Executing Instructions
The ALU performs the actual operation such as calculation, comparison,
or data movement as per the decoded instruction.
Example: Executing ADD 5 + 10 gives the result stored in a register.
2.4 Controlling the System
, The microprocessor sends control signals to manage timing and
coordination among system components.
Example: Sending print signals to the printer after data processing.
2.5 Performing Arithmetic and Logical Operations
The ALU handles all mathematical and logical tasks essential for
decision-making.
Example: Comparing marks using IF marks ≥ 50 THEN PASS.
2.6 Communication and Data Transfer
The processor exchanges data with memory and I/O devices using
address, data, and control buses.
Example: Transferring data from RAM to storage while saving a file.
3. Instruction Cycle
It is the continuous process of fetching, decoding, and executing
instructions to perform tasks rapidly.
Example: A modern processor executes billions of cycles per second.
4. Practical Illustration
The microprocessor works like a reader following instructions from a
bookshelf (memory) and delivering results (output).
3. Components of Microprocessors:
Component Type Function
ALU Core unit Performs arithmetic and
logic operations
IP Special Register Holds the address of the
next instruction
CU Control Unit Controls execution of
instructions
EU Functional Unit The EU is responsible for
execution and processing.
Registers Storage Temporary data storage
BIU Interface / Data Transfer The BIU is responsible for
Unit communication and
fetching.