Von Neumann Architecture and Computer Peripherals

Posted on Dec 2, 2024 in Computers

Von Neumann Architecture

This architecture, pioneered by John von Neumann, introduced the concept of storing programs in memory alongside data, allowing the CPU to execute them sequentially. This fundamental principle underpins the operation of all modern computers.

Central Processing Unit (CPU)

  • Control Unit (UC): Interprets and manages machine instructions, generating control signals to execute operations.
  • Instruction Decoder (OI): Decodes instructions fetched from memory.
  • Clock: Synchronizes operations by providing a timing signal.
  • Select: Orders instructions and synchronizes them with the clock.
  • Arithmetic Logic Unit (UAL): Performs arithmetic and logical operations on data.
  • Floating-Point Unit (FPU): Handles floating-point calculations.

CPU Registers

  • Visible to the User: Data Register, Address Register, Condition Register.
  • Control and Status: Program Counter (CP), Instruction Register (IR), Memory Address Register (RDM), Memory Buffer Register (RIM).

Bus Communications

Different computer units, including memory, communicate through buses. These electrical or optical lines carry information between components, with each line transmitting a single bit. Bus width, measured in bits (e.g., 16, 32, 64), determines the amount of data transferable at a time.

Bus Types

  • Data Bus: Enables data exchange between the CPU and external devices (memory, peripherals). Speed is measured in MHz or GHz.
  • Address Bus: Transmits memory addresses between the CPU and memory, specifying data locations. A larger bus allows access to more memory locations.
    • 10-bit Bus: 2^10 = 1024 positions
    • 16-bit Bus: 2^16 = 65536 positions
  • Control Bus: Generates control pulses from the Control Unit to govern computer operations. The number of bits is less critical here.

Memory

  • Cache: Very fast memory between CPU and RAM, storing frequently accessed data.
  • RAM: Fast memory holding currently running programs and data.

Peripherals

Input Peripherals

Devices used to input information into the computer. Examples: keyboard, mouse, webcam, scanner, microphone, barcode scanner, joystick, touchscreen.

Output Peripherals

Devices that display information processed by the computer. Examples: monitor, printer, speakers, headphones, fax.

Input/Output Peripherals

Storage Peripherals

Devices that store and retrieve data for the processor. Examples: hard drive, CD/DVD/Blu-ray reader/recorder, flash drive (USB), magnetic tapes, removable disks.

Communication Peripherals

Devices that send and receive data. Examples: fax-modem, network card, wireless card, Bluetooth adapter, serial/parallel port, infrared port, hub.

Computer Operation

  1. Power-on: Power supply energizes hardware components, including the CPU.
  2. BIOS Initialization: CPU activates the BIOS (Basic Input/Output System) chip in ROM, which runs POST (Power-On Self-Test).
  3. Hardware Check: BIOS checks basic devices (CPU, RAM, keyboard).
  4. OS Loading: BIOS locates and loads the operating system (OS) into RAM.
  5. OS Execution: OS takes control and runs programs.
  6. Shutdown: OS saves data, and RAM is cleared.

Computer Software

Software comprises programs, instructions, and rules that enable a computer to perform tasks.

Software Classification

  • System Software: Enables the computer hardware to function correctly. Examples: operating systems, drivers, diagnostic tools.
  • Application Software: Helps users perform specific or general-purpose tasks. Examples: office applications, graphics software, web browsers, calculators.
  • Programming Software: Aids in developing new software. Provides tools and interfaces for creating programs. Examples: Visual Basic, C++, Java, Borland.