This document provides an overview of computer organization and architecture. It discusses the main components of a computer system including the central processing unit (CPU), bus, internal communication, instruction set, and machine cycle. The CPU contains a control unit, arithmetic logic unit (ALU), and registers. It coordinates the execution of instructions by fetching, decoding, and executing them via the ALU. The bus allows components like the CPU, memory, and I/O devices to communicate. It consists of address, data, and control buses. The machine cycle involves four stages - fetch, decode, execute, and store - to process instructions.

1. COMPUTER ORGANIZATION AND
ARCHITECTURE
BY
KAVIYA.S 15/09/2005
I-A

2. COMPONENTS :
◦ INTRODUCTION
◦ CENTRAL PROCESSING UNIT(CPU)
◦ THE BUS
◦ INTERNAL COMMUNICATION
◦ INSTRUCTION SET
◦ MACHINE CYCLE

3. INTRODUCTION :
◦ Architecture focuses on the design and structure of the computer
system.
◦ Computer organization refers to the physical components and how they
interact.
◦ Topics include Central Processing Unit, Internal Communication,
Machine Cycle, The Bus, Instruction Set.

4. Central Processing Unit:
◦ The CPU is the brain of the computer, responsible for executing instructions.
◦ It consists of three main components: The Control Unit, The Arithmetic logic Unit (ALU) and Registers.
◦ The control unit coordinates the execution of instructions by fetching, decoding and executing them.
◦ The ALU performs arithmetic and logical operations, such as addition, subtraction and comparisons.
◦ Registers are small, fast memory units used to store data and instructions for immediate access.
◦ The CPU interacts with other components, such as memory and input/output devices, to perform tasks.

6. The Bus:
◦ The bus is like a highway that allows different components of a computer system to
communicate.
◦ There are different types of buses, such as the address bus, data bus, and control bus.
◦ The address bus connects the CPU, memory, and other major components.
◦ The data bus carries data between the CPU, memory, and input/output devices.
◦ The control bus carries control signals to coordinate the activities of the components.

8. Internal Communication:
◦ Internal communication refers to the exchange of data and control signals within a computer
system.
◦ It involves the interaction between different components, such as the CPU, memory, and
input/output devices.
◦ Internal communication in computer architecture involves buses, registers, clock signals, control
units, and memory access.
◦ It enables data transfer and coordination within the CPU.
◦ Pipelining improves efficiency.

9. Instruction Set:
◦ The instruction set is a collection of commands that the CPU can understand and execute.
◦ It defines the operations that the CPU can perform, such as arithmetic, logical, and data
movement.
◦ Instructions are represented in binary format, and each instruction has an opcode and operands
◦ Different CPUs have different instruction sets, such as x86, ARM, and MIPS.
◦ The instruction set architecture (ISA) specifies the interface between software and hardware

11. Machine Cycle:
◦ A machine cycle refers to the sequence of operations performed by the CPU to fetch,
decode, execute, and store instructions. It plays a crucial role in the overall functioning
of a computer system.
◦ During the machine cycle, the CPU performs four stages: fetch, decode, execute, and
store.
1. Fetch : The CPU retrieves the next instruction from memory.
2. Decode: The CPU interprets the instruction and determines what operation to perform
3. Execute: The CPU carries out the operation specified by the instruction.
4. Store : The CPU stores the result of the operation in memory or a register. Each stage is essential for the proper
execution of instructions in a computer system.