GCSE J277 Unit 1.2 | Memory and Storage – Part 1

Specification and Learning Objectives

• Key Topics to Study:

  • The need for primary storage.

  • Difference between RAM and ROM.

  • Purpose of ROM in a computer system.

  • Purpose of RAM in a computer system.

  • Virtual memory.

  • Need for secondary storage.

  • Common types of storage (optical, magnetic, solid-state).

  • Suitable storage devices for specific applications.

  • Advantages and disadvantages of different storage technologies related to:

    • Capacity

    • Speed

    • Portability

    • Durability

    • Reliability

    • Cost

Virtual Tour Inside a Computer

• Key Components:

  • CPU (Central Processing Unit)

  • BIOS

  • RAM (Random Access Memory)

  • ROM (Read-Only Memory)

• Connections:

  • Southbridge connects ROM, BIOS, and I/O devices to CPU.

  • Northbridge connects high-speed components such as GPU and RAM.

CPU Overview

• Components:

  • Arithmetic Logic Unit (ALU): Performs calculations and logic.

  • Control Unit: Decodes instructions and controls data movement.

  • Cache: Fast-access memory for frequently used instructions and data.

  • Registers: Small amounts of fast memory used for instruction fetching and execution.

• Factors Affecting Speed:

  • Number of cores.

  • Clock speed.

  • Cache size.

RAM and ROM

RAM (Random Access Memory)

• Purpose: Temporary storage of instructions and data for currently executing programs.

• Characteristics:

  • Volatile: Contents lost when powered off.

  • Read/write: Can be both read from and written to.

ROM (Read-Only Memory)

• Purpose: Holds instructions for booting the computer (bootstrap).

• Characteristics:

  • Non-volatile: Retains contents when powered off.

  • Read-only: Cannot be written to.

Virtual Memory

• Definition: Part of the hard disk acts as additional memory.

• Purpose: Needed when physical RAM is insufficient for all open programs/data.

• Drawback: Slower execution since instructions must transfer from virtual to RAM for processing.

Secondary Storage Need

• Reasons for Secondary Storage:

  • ROM is read-only; cannot save files.

  • RAM is volatile; cannot save files long-term.

• **Types of Secondary Storage: **

  • Magnetic: Data stored using magnetism.

  • Solid-state: Data stored using semiconductor chips.

  • Optical: Data stored using pits and lands.

• Definitions:

  • Primary storage: RAM, ROM, registers, cache.

  • Secondary storage: OS, programs, data held when not in use.

  • Tertiary storage: Backups and archives.

Examples of Secondary Storage

1. Hard Disk

• Type: Magnetic

• Uses: Internal storage for PC/laptop.

• Characteristics: Moving head, requires defragmentation for optimal performance.

2. Flash Memory

• Type: Solid-state

• Uses: Storing image files, lower power, quiet operation.

• Characteristics: No moving parts, limited read/write cycles.

3. CD-R

• Type: Optical

• Uses: Storing music, backup files.

• Characteristics: Read/write laser technology.

4. Solid-State Drive (SSD)

• Type: Solid-state

• Uses: Replacement for hard disks.

• Characteristics: Faster load times, quieter operation.

5. Blu-ray Disc

• Type: Optical

• Uses: Storing films, games.

• Characteristics: Higher capacity than CDs.

Suitability of Devices

• Scenario 1: Solid-state memory cards for helmet-mounted cameras are:

  • Resistant to impacts.

  • Compact and lightweight.

• Unsuitable: Hard disks are easily damaged and larger.

• Scenario 2: Downloading vs. physical games:

  • Hard disk space limitation.

  • Ease of installation vs. physical media preference.

  • Instant access vs. reliance on broadband connection.

• Scenario 3: Backing up photos using DVD-R:

  • Advantages: Low cost, durable.

  • Disadvantages: Slow data writing, limited capacity.

• Scenario 4: Chosing a storage options:

  • 6TB HDD for maximum storage.

  • 2TB SSD for speed.

  • Hybrid option for a balance of speed and capacity.