CSE2009-COA-Module 1

Module 1: Basic Structure of Computers

Introduction

  • Overview of the fundamental concepts of Computer Organization and Architecture.

Topics to be Covered

  • Introduction

  • Types of Computer

  • Functional Units of Computer

  • Basic Operational Concept

  • Bus Structure

  • Performance of the Computer

  • Number Representation

  • Memory Location and Address

  • Instruction and Instruction Sequencing

  • Generation of Computer

Types of Computers

Classification

  • Computers classified based on:

    • Size

    • Cost

    • Computational power

  • Categories include:

    • Microcomputers

    • Mainframes

    • Minicomputers

    • Servers

    • Supercomputers

Microcomputer

  • Designed for individual use: PCs, workstations, notebooks.

Laptop Computer

  • Portable notebooks as compact versions of PCs.

Workstation

  • Powerful desktops for specialized tasks.

    • More computational power than PCs.

    • High-resolution graphics screens.

    • Designed for single users.

Mainframe

  • Supports hundreds/thousands of users simultaneously.

    • Manages large data storage and processing.

Minicomputer

  • Midsized, between workstations and mainframes.

    • Multi-user support, 10 to hundreds of users.

    • Evolved into mid-range servers.

Server

  • Serves data to clients via a LAN.

    • Purpose: data supply and management.

Supercomputer

  • High-performance for scientific/engineering tasks.

    • Capable of managing large databases and heavy computations.

    • Executes millions of instructions per second.

Functional Units of a Computer

Main Parts

  • Input Unit

  • Output Unit

  • Memory Unit

  • Arithmetic Logic Unit (ALU)

  • Control Unit

Input Devices

  • Accepts coded information from users:

    • Examples: Keyboard, Mouse, Scanner, Joystick, etc.

Output Devices

  • Sends processed results to outside world:

    • Examples: Monitors, Printers, Projectors, etc.

Storage Devices

  • Keeps data when powered off:

    • Examples: Hard disks, CDs, Zip disks, etc.

Memory Unit

  • Stores programs and data:

    • Primary Storage: Fast, electronic speed memory during execution.

    • Secondary Storage: Slower, long-term data storage.

Memory Specifications

  • Word Address: Retrieval in a single operation.

  • Word Length: Number of bits typically ranges from 16 to 64.

  • Memory Access Time: Time to access one word.

Arithmetic and Logic Unit (ALU)

  • Performs arithmetic operations using high-speed registers.

Control Unit (CU)

  • Manages operations among functional units and controls data transfers.

Basic Operational Concepts

Instruction Execution

  • Example: Add instruction involves fetching from memory and adding operands.

  • Steps:

    1. Fetch instruction to processor.

    2. Fetch operand, perform addition, and store in register.

Instruction Variations

  • Alternate approaches with different instructions for the same task.

Bus Structures

  • Definition: A group of lines connecting multiple devices (Data bus, Address bus, Control bus).

    • Connects CPU, memory, and I/O devices.

Performance of a Computer

  • Determines execution speed of programs.

  • Influenced by:

    • Hardware design

    • Instruction efficiencies

    • Compiler performance

Factors Affecting Performance

  • Speed of processor, memory, and I/O devices.

  • Total execution time derived from:

    • Instruction count.

    • Cycle time.

    • Execution steps.

Number Representation

Binary and Character Codes

  • Representation systems:

    1. Sign-and-magnitude

    2. 1's Complement

    3. 2's Complement

Example Representations

  • +5 as 0101 (Sign magnitude) and -5 as 1101.

Memory Locations and Addresses

Organization of Memory

  • Consists of storage cells, with particular addressing for accessing data.

  • Address Space: Size determined by bit lengths (e.g., 24-bit, 32-bit).

Endianness in Memory

  • Big-Endian: Most significant byte at lowest address.

  • Little-Endian: Least significant byte at lowest address.

Instruction and Instruction Sequencing

Types of Operations

  • Data transfer, arithmetic operations, program control, I/O transfer.

Register Transfer Notation (RTN)

  • Simplified notation for data movement in computer architecture.

Assembly Language Notation

  • Represents machine instructions in readable format.

RISC vs. CISC

  • RISC: Simple, fixed instruction lengths with less cycles.

  • CISC: More complex instructions with variable lengths.

Generations of Computers

  • Sequentially evolved design characteristics and capabilities.