COA MOD1

Computer Organization & Architecture

Module Overview

• Module 1: Overview of basic computer architecture and organization.

  • Focus includes:

    • Basic structure of computers, functional units, and operational concepts.

    • Memory and addresses: Little endian and Big endian.

    • Instructions, instruction sequencing, and addressing modes.

    • Basic processing unit fundamentals: instruction cycle, execution, single bus, and multiple bus organization.

  • Course Outcome 1: Recognize relevance of basic components, I/O organization, and processing unit in a digital computer (Cognitive knowledge: Remember).

Definition of a Computer

• A computer is an electronic device that manipulates information or data, capable of storing, retrieving, and processing data.

• Functions performed by a computer:

  • Accepts input for processing.

  • Stores instructions for data processing.

  • Processes information according to the instructions.

  • Provides processed data as output.

Types of Computers

• Computers can be categorized based on size, cost, and computing power:

  • Personal Computers (PC): General-purpose computers for individual use (desktops).

  • Notebook/Laptops: Portable versions of PCs.

  • Tablets/Smartphones: Compact, pocket-friendly versions of PCs.

  • Workstations: Specialized computers for tasks like engineering and graphic design, more powerful than typical PCs.

• Additional Categories:

  • Embedded Computers: Integrated into devices (e.g., cars, appliances) to control functions.

  • Servers: Handle complex tasks for multiple users (e.g., hosting websites).

  • Enterprise Systems (Mainframes): High reliability and processing power for large-scale applications.

  • Supercomputers: Perform complex calculations (e.g., weather forecasting).

Computer Organization & Architecture

• Computer Organization: Focuses on how hardware components operate and are connected.

• Computer Design: Determination of hardware specifications and configurations.

• Computer Architecture: Structure and behavior as seen by the user, including instruction formats and addressing techniques.

  • Architectural design specifies functional modules and their interconnections.

Functional Units of a Computer

• Main Components:

  • Input Unit

  • Output Unit

  • Memory Unit

  • Arithmetic and Logic Unit (ALU)

  • Control Unit

• These units operate independently but collaborate to perform computations.

Information in a Computer - Instructions

• Instructions: Commands for operations in the computer:

  • Transfer information within the computer or between devices.

  • Perform arithmetic and logic operations.

  • A sequence of instructions is a program stored in memory.

Information in a Computer - Data

• Data: Operands on which instructions operate, can be:

  • Numbers

  • Encoded characters

  • Information represented in binary form (bits).

Input Unit

• Responsible for converting binary information from input devices (e.g., keyboard, mouse) to a format recognized by the computer.

Memory Unit

• Stores:

  • Program instructions, data, and computation results.

• Types of Memory:

  • Primary Memory (Main Memory): Fast semiconductor memory (ROM, RAM).

  • Secondary Memory: Non-volatile storage (e.g., HDD, SSD).

RAM vs Hard Disk Drive (HDD)

• RAM:

  • Primary memory, volatile, fastest access, small storage capacity.

• HDD:

  • Secondary memory, non-volatile, larger capacity, slower access.

Arithmetic and Logic Unit (ALU)

• Executes arithmetic (addition, subtraction) and logic (comparisons) operations based on program instructions.

• Uses registers for faster data access.

Control Unit (CU)

• Directs operation by synchronizing the functions of other units with timing signals.

Basic Operational Concepts

1. Program instructions and data stored in main memory.

2. CPU fetches instructions sequentially, decodes, and executes them using ALU.

3. Results stored back in memory or output devices.

Instruction Cycle

• Includes fetching, executing, and preparing for the next instruction in a sequential manner.

Computer Buses

• Buses are electrical connections facilitating communication between hardware components (CPU, memory, I/O devices).

• Types of Buses:

  • Data Bus

  • Address Bus

  • Control Bus

Memory Locations and Addresses

• Main memory comprises storage cells for binary digits.

• Each memory location has a distinct address.

• Word Size: Indicates data handled at once by the CPU, determined by the CPU's architecture.

Address Assignment (Endianness)

• Big-endian: Most significant byte stored first.

• Little-endian: Least significant byte stored first.

Accessing Memory - Operands and Results

• Basic Operations:

  • Fetch (Read) and Store (Write) control movement of data to/from CPU and main memory.

Classification of Instructions**

• Categories:

  • Data Transfer Instructions (e.g., LOAD, STORE)

  • Arithmetic & Logic Instructions (e.g., ADD, SUB)

  • Control Instructions (e.g., JMP, JZ)

  • I/O Instructions for data input/output operations.

Conditional Codes

• Maintain status of operations in the ALU (flags for zero, carry, overflow).

Addressing Modes

• Techniques for locating operands in instructions, influencing how operands are accessed:

  • Immediate, Register, Absolute, Indirect, Index, and others.

• Effective Address: Memory address where operand is found.

Register Transfer Notation (RTN)

• Describes data transfer operations within the CPU.

• Examples of instructions represented using RTN for clarity.