Von Neumann Architecture and Computer Fundamentals

Posted on Jan 6, 2025 in Electronics

Von Neumann Architecture

It is standard to store data in memory and execute it in a processor. From there, all computers work this way.

  • CPU
    • Control Unit (CU): It is in charge of interpreting instructions and managing the machine, generating the necessary signals for operations control.
    • Instruction Decoder (ID)
    • Clock: Marks the time.
    • Selector: Marks the order of instructions and synchronizes with the clock.
    • Arithmetic Logic Unit (ALU): Its function is to operate the data that it receives preferentially from the CU. It performs arithmetic and boolean operations.
    • Floating Point Unit (FPU)
      • Also known as:
      • Math coprocessor
      • Numerical Processing Unit (NPU)
      • Numerical Data Processor (NDP)
  • Registers
    • Visible to users
      • Address register
      • Data register
      • Condition register
    • Control and status
      • Program counter (PC)
      • Instruction register (IR)
      • Memory address register (MAR)
      • Memory buffer register (MBR)

Communication Buses

The different units, the memory, and the inputs communicate through buses, which are electrical or optical lines that transmit information between units. Always one bit per bus at a time. The amount of data that a computer can process at once marks if a computer is 16, 32, or 64 bits.

Types of Buses

  • Data Bus: Allows the exchange of data between the CPU and external units (memory, peripherals…). Speed is in MHz or GHz.
  • Address Bus: Transmits the address between the CPU and the memory where the data is located. It is the most important bus because it allows access to more data.
    • Bus 10 bits -> 2^10 = 1024 positions
    • Bus 14 bits -> 2^16 = 65536 positions
  • Control Bus: Generates control impulses from the CU to govern the computer. The importance is not the number of bits.

Cache: Very fast memory between the CPU and RAM, containing data that will surely be read soon.

RAM: Fast memory, with data and programs that will possibly be executed or have been executed and will be executed again.

Computer History

In the mechanical era, punch cards and magnetic tapes were used. In the electronic era, computers are smaller and lighter.

In the mechanical age, the information was more reliable than in the electronic age.

  • Mechanical: Babbage’s Difference Engine, Babbage’s Analytical Engine, Blaise Pascal’s calculating machines.
  • Electronic: Maniac, IBM 360.

Peripherals

1. Input Peripherals

Those that serve to input information into the machine.

Examples: Keyboard, mouse, webcam, scanner, microphone, barcode scanner, joystick, touch screen.

2. Output Peripherals

They show the information once processed by the machine.

Examples: Monitor, printer, speakers, headphones, fax.

3. Input/Output Peripherals

3.1 Storage Peripherals

They are in charge of storing or saving data to the processor. They perform both input and output functions. They are a special group because they cannot show information to the user.

Examples: Hard disk, CD/DVD/Blu-ray reader/recorder, flash memory (USB), magnetic tapes, diskettes, removable drives.

3.2 Communication Peripherals

They are similar to storage peripherals in that they can receive or send data. Therefore, they perform input/output functions.

Examples: Fax-modem, network card, wireless card, Bluetooth, serial port, infrared, USB.

Computer Functional Description

When we turn on a computer, these steps occur internally:

  1. When the computer is turned on, the power supply sends current to all hardware devices, including the CPU.
  2. When the CPU receives the current, it sends the first order to the ROM chip of the BIOS (Basic Input/Output System) where the POST (Power-On Self-Test) routines are recorded.
  3. The test is executed. If the BIOS does not find anything wrong (it checks the status of basic devices, CPU, RAM, keyboard…), it continues with the location of the operating system.
  4. The BIOS loads the operating system. The logo of Windows or Linux appears on the screen. The operating system is loaded into RAM to be executed later by the CPU.
  5. * If several operating systems are installed, the BIOS will let us choose the boot order. The BIOS always loads the first position of the hard drive.
  6. Once any program is executed, it follows this process: Mass Storage -> RAM -> CPU.
  7. When the computer is turned off, all registers and RAM are completely emptied.

Computer Software

Definition: Set of computer programs, rules, and instructions to execute certain tasks on a computer.

Software Classification

Based on the type of service or work performed:

  • System: Software that allows the hardware of a computer to function correctly. It is used to manage the physical part of the computer. Examples: Operating systems, drivers, diagnostic tools.
  • Application: Software that helps us perform specific or general-purpose tasks, providing user support. Examples: Office automation applications, graphic applications, web browsers.
  • Programming: Software that helps users develop new software. It allows the user to create different programs in an easier way. It provides a more direct interaction with the system and easier compilation. Examples: Visual Basic, C++, Java, Borland.