Chapter 3(1)

Page 1: Introduction to Von Neumann Architecture

Components

  • Input/Output

  • Central Processing Unit (CPU)

  • Memory Unit

    • RAM

    • ROM

Other Units

  • ALU (Arithmetic Logic Unit)

  • CU (Control Unit)

  • MAR (Memory Address Register)

  • PC (Program Counter)

  • MDR (Memory Data Register)

  • CIR (Current Instruction Register)

  • ACC (Accumulator)

Buses

  • Control Bus

  • Data Bus

  • Address Bus

Storage

  • Secondary Storage (e.g. HDD, SSD, removable disks, CDs)

Key Functionality

  • Load executable code as needed.

Page 2: Memory Types

Definitions

  • Primary Memory:

    • The computer's main storage area, directly interacting with the CPU.

    • Temporarily holds data and instructions during processing.

  • Secondary Storage:

    • Non-volatile storage devices like HDDs and SSDs.

    • Used for long-term data storage and retrieval.

Page 3: Memory Interaction

  • Primary Memory:

    • Direct interaction with CPU for processing instructions.

  • Secondary Storage:

    • Independent from CPU operations, focusing on data retention.

Pages 4-8: Compare and Contrast Memory Types

Primary vs. Secondary Storage

  • Primary Memory (RAM/ROM):

    • Key data storage for running the computer; includes executable and boot-up code.

    • Directly addressable by the CPU, ensures high retrieval speed.

    • Examples: RAM, ROM, cache memory.

  • Secondary Storage:

    • Stores applications, data, and files.

    • Not directly addressable by the CPU, leading to lower retrieval speed.

    • Examples: HDD, SSD, DVD, memory stick, Blu-ray disc.

Page 9: Memory Definitions Revisited

  • Primary Memory:

    • Main temporary storage during processing

  • Secondary Storage:

    • For long-term data retention independent of CPU operations.

Page 10: RAM Overview

RAM (Random Access Memory)

  • Definition: Full term for RAM, accessible memory.

  • Allows direct access to any memory location regardless of order previously accessed.

  • Data fetched from secondary storage is temporarily held in RAM during execution.

Page 11: Features of RAM

  • Read/Write Capability: Can be altered by user or computer.

  • Temporary Storage: Holds data, applications, and OS parts currently in use.

  • Volatile Nature: Contents are lost when powered off.

  • Impact on Speed: Larger RAM results in faster computer operations.

Page 12: ROM Overview

Read-Only Memory (ROM)

  • Definition: Cannot be changed or written to; serves as permanent storage.

  • Characteristics: Non-volatile and retains data after power off, frequently used for start-up tasks.

Pages 13-17: Compare and Contrast RAM and ROM

Key Differences

  • RAM:

    • Temporary, volatile, read/write capabilities.

    • Used to store OS and current processes.

  • ROM:

    • Permanent, non-volatile, only readable.

    • Used for initial startup data.

Page 18: HDD (Hard Disk Drive) Overview

Components of HDD

  • Parts: Platters, electromagnet, read-write heads, track, and sector.

  • Data stored on magnetic surfaces, platters spin at high speed.

Page 19: HDD Access Speed

Why is HDD Slow?

  • Slow access due to necessary head movements to read data blocks.

  • Latency affects performance based on waiting time for data.

Page 20: Fragmentation in HDD

HDD Fragmentation

  • Non-adjacent allocation of sectors leads to performance degradation.

  • Defragmentation software can optimize access times.

Page 21: Removable HDD

Removable Hard Disk Drives

  • External HDDs that connect via USB.

  • Used for backup and data transfer between computers.

Page 22: SSD (Solid State Drive) Overview

General Information

  • No moving parts, data access at consistent speeds.

Page 23: How SSD Stores Data

  • Data Representation: Stored as 0s and 1s in transistors.

  • How It Works: Uses electron movement through logic gates for storage.

Page 24: Advantages/Disadvantages of SSD vs. HDD

Advantages of SSD

  • Light, reliable, thinner, faster access, cooler operation.

Disadvantages of SSD

  • Poor longevity compared to HDD; limited use in all servers.

Pages 25-29: Optical Media

Types of Optical Media

  • Types: CD, DVD, Blu-ray

  • Storage Mechanics: Data stored as pits and lands; read by laser.

Differences Between CD and DVD

  • DVDs have larger storage capacity and can be dual-layered.

Blu-ray Features

  • Uses a blue laser for higher storage capacity; faster data transfer rates.

Pages 30-41: Exam Questions

Magnetic Storage Device Overview

  • Describe the operation of magnetic storage.

  • Key components and function of HDD.

Similarities and Differences between HDD and SSD

  • Overview of differences (moving parts, storage type, speed, etc.).

Example Questions

  • Examples of primary and secondary storage devices.

  • Explain why magnetic storage might be chosen over SSD in serving.