Von-Neumann Computer Architecture Overview

Von-Neumann Computer Architecture

• Proposed in 1945, later known as Von-Neumann architecture.
• Two historical computer types:
  • Fixed Program Computers: Specific functions, not reprogrammable (e.g., calculators).
  • Stored Program Computers: Programmable, store programs and data in the same memory.
• Modern computers use the stored-program concept, introduced by John Von Neumann.
• This design allows for easier reprogramming of the computer.

Central Processing Unit (CPU)

• Known as Instruction Set Architecture (ISA) computer.
• Composed of three basic units:
  • Central Processing Unit (CPU)
  • Main Memory
  • Input/Output Unit (I/O)

Central Processing Unit (CPU) components

• Control Unit (CU): Manages processor control signals, directs input/output flow, fetches instructions, and controls data movement.
• Arithmetic Logic Unit (ALU): Performs calculations (addition, subtraction, comparisons), logical operations, and bit shifting.
• Registers: High-speed storage areas for data processed by the CPU, including:
  • Accumulator: Stores calculation results.
  • Program Counter (PC): Tracks the next instruction location.
  • Memory Address Register (MAR): Stores memory locations of instructions/data.
  • Memory Data Register (MDR): Stores instructions/data fetched from/stored in memory.
  • Current Instruction Register (CIR): Stores the recently fetched instruction.
  • Instruction Buffer Register (IBR): Stores instructions not to be executed immediately.

Buses

• Data Bus: Carries data between memory, I/O devices, and the processor.
• Address Bus: Carries addresses of data (not data itself) between memory and processor.
• Control Bus: Carries control commands and status signals to coordinate all computer activities.

Input/Output (I/O) Devices

• Input devices: Gather data to be processed (e.g., keyboard, mouse, microphone).
• Output devices: Provide results from processing (e.g., monitor, printer, speakers).

Von Neumann Bottleneck

• Limitations in the speed of fetching instructions by Von-Neumann architecture:
• Instructions must be fetched sequentially from memory prior to execution.
• Each process can only carry out one step at a time.

Hardware Components of Computer Systems

• Computer hardware includes all physical parts of a computer, distinguishing them from software.
• Internal Components:
  • Motherboard
  • CPU (central processing unit)
  • RAM (Random Access Memory)
  • Hard Drive (physical storage)
  • Solid-State Drive (SSD)
  • Optical Drive
  • Heat sink
  • Graphics Processing Unit (GPU)
• External Components:
  • Mouse
  • Keyboard
  • Microphone
  • Camera
  • Touchpad
  • USB Flash Drive
  • Memory Card
  • Monitor
  • Printer
  • Speaker
  • Headphones
  • Network Interface Card (NIC)

Utility Programs

• System Utilities:

  • Memory manager
  • Antivirus/firewall
  • Registry checker/cleaner
  • Package installer
  • File explorer

• File Management Utilities:

  • Data archivers
  • Software backup tools
  • File compression tools
  • File managers

• Storage Device Management Utilities:

  • Disk cleanup
  • Partition management
  • Formatting
  • Disk space allocation
  • Defragmentation

• Miscellaneous Utilities:

  • Data generators
  • HTML checkers
  • Hex editors

• Advantages of Utility Programs:

  • Efficient data and file management
  • Removal of unnecessary files
  • System security enhancement
  • Easy file location and access
  • File recovery
  • System performance enhancement

• Disadvantages of Utility Programs:

  • System instability due to altered settings
  • Incorrect software identification as security threats
  • Resource consumption
  • Incompatibility issues with certain operating systems/hardware
  • High costs for specialized programs
  • User error can lead to data loss/system instability

Language Translators

• Translates high-level programming languages (e.g., Python, Java) into low-level machine code (0s and 1s) that the CPU understands.

• Types of Translators:

  • Compiler: Converts the entire program at once; faster execution speed but slow compilation time, dependent on hardware/OS
  • Interpreter: Converts and executes the program line by line; quick execution speed but slower execution than compiler
  • Assembler : Converts assembly language to machine code in step by step manner.

The Internet and the World Wide Web (WWW)

• The Internet: A vast global network of interconnected computer networks used for communication, information sharing, and resource access.
• WWW (or Web): A system of interconnected documents and resources accessed through the internet and linked by hyperlinks and URLs.

Network Devices

• Repeater: Signals become weak or corrupted. Copies signal bit by bit, regenerates and extends network length.
• Hub: Multi-port repeater; sends data to all connected devices simultaneously (broadcasting) which leads to congestion.
• Bridge: Operates at data link layer. Filters data by reading source/destination MAC (Media Access Control) addresses; used to connect two LANs.
• Switch: Multi-port bridge, checks the data before forwarding it; improves efficiency by dividing collision domain into smaller segments; prevents data loss and boosts performance.
• Router: Routes data packets based on IP (Internet Protocol) addresses; connects LANs and WANs.
• Gateway: Acts as an interpreter between two different network systems using dissimilar protocols.
• Network Interface Card (NIC): Attaches a computer to a network
• Brouter: Combines both bridging and routing functionalities.
• Other Devices: Other devices, like modem, are found in enterprise computer networks..

Types of Area Networks (LAN, MAN, WAN)

• LAN: Local Area Network: A network covering a small geographical area (e.g., office, home).
• MAN: Metropolitan Area Network: Bigger than LAN but smaller than WAN, serving a city. - Covers a geographical area of 5-50 kilometers, and supports higher speeds.
• WAN: Wide Area Network: Network spanning a large geographic area, linking multiple MANs or LANs (e.g., global networks).
• PAN: Personal Area Network: A network connecting personal devices in a close range (e.g., Bluetooth, Wi-Fi).
• EPN: Enterprise Private Network: A private network used by an enterprise.
• VPN: Virtual Private Network: Encrypts data transmitted through a public network to ensure confidentiality.

Transmission Modes

• Simplex: Unidirectional communication (e.g., keyboard to monitor).
• Half-duplex: Bidirectional communication, but only one direction at a time (e.g., walkie-talkie).
• Full-duplex: Bidirectional communication, both directions simultaneously (e.g., telephone).

Transmission Media

• Guided Media: Signals are transmitted through physical mediums like cables (e.g., twisted pair, coaxial, fiber optic.)

  • Twisted pair cable: Inexpensive, easy to install, low bandwidth, susceptible to interference, shorter distances.
  • Coaxial cable: Higher bandwidth than twisted pair, more expensive and bulkier.
  • Optical fiber cable: Highest bandwidth, less susceptible to interference, immune to electronic noise, but costly & fragile.

• Unguided Media: Signals are broadcast through air or space (e.g., radio waves, microwaves, infrared).

  • Radio waves: Omni-directional, penetrate buildings, easily generated, moderate security.
  • Microwaves: Uni-directional, line of sight, high bandwidth, susceptible to interference, ideal for long distances.
  • Infrared: Short-range communication, cannot penetrate obstacles (e.g., remote controls).

Explore the fundamentals of Von-Neumann architecture, a significant model in computer design proposed in 1945. This quiz covers key concepts including fixed and stored program computers, along with details about the Central Processing Unit (CPU) and its components such as the Control Unit and Arithmetic Logic Unit.