When you press the power button on your computer, several hidden steps take place before the operating system (like Windows) appears on the screen. These early steps are controlled by special built- in software called firmware. In this section, you will learn what firmware is, how the Basic Input/Output System (BIOS) and Unified Extensible Firmware Interface (UEFI) help start the computer, and how you can access basic startup settings if needed.
2.4.1 Role of BIOS / UEFI in Computer Startup
All computers have special software built into the motherboard called firmware. It is not stored on the hard drive and does not get deleted when the computer is turned off. Firmware gives the computer basic instructions on how to start.
Two common types of firmware are:
- BIOS older firmware software shows a basic, text- only menu and works with the keyboard only.
- UEFI newer type of firmware software, supports a graphical menu that uses both mouse and keyboard, and larger hard drives.
Role of BIOS/UEFI in Starting the Computer:
- Checks if the hardware is working correctly (like RAM, keyboard, and hard drive).
- Finds the boot device (USB, hard disk, etc.) and starts the operating system.
- Allows users to change system settings like date, time, and boot order.
BIOS was first developed in the 1980s, while UEFI is now used in most modern computers because it is faster and more secure.
2.4.2 The POST Test
POST stands for Power- On Self- Test. It is the first thing the firmware does after the computer is turned on. POST checks the most important hardware to make sure everything is working properly. If all parts are fine, the computer continues to load the operating system. If something is wrong, it may beep or show an error message on the screen.
Example: If the RAM is missing, the computer will beep continuously.