System Architecture

What is Computer Systems Architecture?

  • The study of the structure, organisation and functionality of computer systems.
  • This includes understanding how hardware and software components interact to perform tasks.

Components:

 Central Processing Unit (CPU)

 The CPU is the brain of the computer, responsible for executing instructions from programs.

  • Components:
    • Control Unit (CU): Directs the operation of the processor.
    • Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations.
    • Registers: Small, fast storage locations within the CPU.
  • Performance Factors:
    • Clock Speed: The speed at which the CPU executes instructions, measured in GHz.
    • Cores: Multiple cores allow for parallel processing, increasing performance.
    • Cache: Small, fast memory for storing frequently accessed data.
    Example:
    • Task Execution: When you run a program, the CPU fetches, decodes and executes the instructions.
    		•

    Memory and Storage

    		 Refer to components that store data and instructions.
    • Types:
      • Primary Memory (RAM): Volatile memory used for temporary storage while programs are running.
      • Secondary Storage: Non-volatile storage for long-term data retention (e.g., HDD, SSD).
    • Characteristics:
      • RAM: Fast, temporary storage used for active processes.
      • ROM: Non-volatile memory containing essential system firmware.
      • Storage Devices: Hard drives and solid-state drives for permanent data storage.

    Example:

    • RAM vs. Storage: RAM is like a workspace for active tasks, while storage is like a filing cabinet for long-term data.

    Input and Output (I/O) Devices

    		 Devices that allow interaction with the computer, either by providing input or receiving output.
    • Types:
      • Input Devices: Keyboards, mice, scanners, etc.
      • Output Devices: Monitors, printers, speakers, etc.
    • Functions:
      • Input Devices: Capture data from the user or environment.
      • Output Devices: Display or present data to the user.

    Example:

    • Keyboard and Monitor: A keyboard inputs data into the system, and a monitor displays output.
    Buses and Communication Buses are communication systems that transfer data between components inside a computer.
    • Types of Buses:
      • Data Bus: Transfers data between CPU, memory, and peripherals.
      • Address Bus: Carries addresses from the CPU to memory or I/O devices.
      • Control Bus: Transmits control signals from the CPU to other components.

    Example:

    • Data Transfer: When reading a file, data travels from storage to RAM via the data bus.
    System Software Software that manages and controls computer hardware.
    • Components:
      • Operating System (OS): Manages hardware resources, provides user interfaces, and runs applications.
      • Drivers: Specialized programs that allow the OS to communicate with hardware devices.

    Example:

    • Operating System: Windows, macOS, or Linux controlling hardware and providing a platform for applications.