How a Computer works?

Introduction to Computer Architecture

Let’s understand how a computer works:

  • Computer takes input from Input devices like Mouse, Keyboard.
  • Inputs from input devices are stored in Input Buffer.
  • CPU periodically checks the input buffer to see if there is any new input.
  • CPU then processes the input using two components: ALU and Control Unit.
  • It loads the necessary program/data into RAM from permanent storage (HDD or SSD).
  • It sends the necessary results to output buffer.
  • Output devices (Monitor) fetch the output from output buffer and shows it on the screen.
Understand with an Example

Let’s use a simple example of using a word application to create a document.

Step 1: Open a Word Application on Mouse Click:
  • Imagine you’re using a mouse to click on the icon of a program (like Microsoft Word) on your computer screen.
  • As soon as you click the icon, the mouse sends an electrical signal (the input) to the computer’s input buffer, a temporary holding area for inputs.
Step 2: CPU Fetches the Input from Input Buffer:
  • Next, the computer’s Central Processing Unit (CPU), the “brain” of the computer, fetches this input from the input buffer.
  • It recognizes that the input is a command to open the word application.
Step 3: CPU Handles the Task:
  • CPU then will load the program into RAM from the permanent storage (HDD or SSD).
  • It also retrieves the necessary files and displays the word application window on your Monitor screen.
Step 4: Typing a Sentence on Keyboard:
  • Now, if you type a sentence, “Hello, world!” on the keyboard.
  • Each keystroke sends an electrical signal (the input) to the input buffer using character encoding and number system.
Step 5: CPU Fetches the Input from Input Buffer:
  • The CPU fetches these inputs from the input buffer.
  • It recognizing the characters you typed.
Step 6: Displaying the Sentence:
  • The CPU processes your input and sends the result (the sentence “Hello, world!”) to the output buffer.
  • You screen (Monitor) will fetch the data from output buffer and display the sentence in word application window.