Computer Bios and Booting Process – JSS2 Computer Hardware & GSM Repair Lesson Note (First Term)

The BIOS (Basic Input/Output System) is a small program on the motherboard that starts the computer, checks the hardware and hands control to the operating system.

Behavioural objectives

By the end of the lesson, students should be able to:

1. State the full meaning of BIOS and say where it is kept.
2. List and explain the four functions of the BIOS.
3. Differentiate between cold booting and warm booting.
4. Arrange the steps of the booting process in order.
5. Name the common settings found in the BIOS setup menu.

What is BIOS?

BIOS stands for Basic Input/Output System, the first program that runs when a computer is switched on.

• Full meaning: Basic Input/Output System.
• Where it is kept: on a small chip on the motherboard.
• Main job: it checks the hardware before the operating system (such as Windows) starts.
• Everyday example: it works like your morning routine, when you check your shoes and bag before leaving for school.
• UEFI: newer computers use UEFI, a modern replacement that does the same work.

What is the CMOS battery?

The CMOS battery is a tiny round battery on the motherboard that keeps the BIOS settings and the clock alive when the computer is off.

• Settings: it remembers the date, time and boot sequence.
• Unplugged computer: the clock keeps running because of this battery.
• Weak battery: the computer may show the wrong date and time after being switched off.

What are the functions of the BIOS?

The BIOS has four main functions, which can be remembered with the letters P.B.S.C.

1. POST (Power-On Self-Test): a quick health check of parts such as the RAM, keyboard and hard drive.
2. Bootstrap Loader: finds the operating system and hands control to it.
3. BIOS Drivers: basic instructions that let the computer use the keyboard and mouse before the main software starts.
4. BIOS Setup: a menu for changing settings such as date, time and password.

What does POST tell us?

• Normal start: all checked parts respond and the computer continues to start.
• Beeps: a pattern of beeps with a black screen can mean a faulty part, such as RAM.
• Beep codes: the meaning of each pattern depends on the make of the computer, so check its manual.

What is booting?

Booting is the process of starting or restarting a computer. There are two types of booting: cold booting and warm booting.

Cold booting

• Meaning: starting a computer that was completely off.
• How: press the power button on the system unit.
• What happens: the computer runs the full start-up routine, including POST.

Warm booting

• Meaning: restarting a computer that is already on.
• How: click Restart in the Start menu, or press the restart button on the system unit.
• Older systems: pressing Ctrl + Alt + Del could restart the computer directly.
• Why it is faster: the power is not cut off, so the software is simply refreshed.
• When it is used: after installing software, or when the computer is “hanging”.

What is the difference between cold and warm booting?

What are the steps in the booting process?

The booting process is the order of events from pressing the power button to seeing the desktop.

1. Press the power button and power reaches the motherboard.
2. The BIOS starts and runs the POST.
3. The BIOS reads the boot sequence to see which device to check first.
4. The bootstrap loader finds the operating system on the hard drive, USB drive or CD.
5. The operating system loads and the desktop appears.

What are BIOS settings?

BIOS settings are the options in the BIOS setup menu that control basic features of the computer.

How do you enter the BIOS setup?

1. Switch the computer on or restart it.
2. Tap the setup key as soon as the first screen appears, such as F2, F10 or Delete.
3. Read the on-screen message, because the key differs between makes of computer.

What can you change in the BIOS setup?

• System date and time: keeps the computer clock correct.
• Boot sequence: sets which device the computer checks first, such as hard drive, USB drive or CD.
• Security: a Supervisor Password stops others from changing the internal settings.

Warning: a wrong setting can stop the computer from starting, so change only what you understand.

What are the key terms?

Teacher’s note

• Lab demonstration: if a computer is available, show students the “Press F2 for Setup” message that flashes during start-up.
• Purpose: it helps students see that the BIOS is real and not only theory.

Evaluation

1. What is the full meaning of BIOS?
2. What is the name of the test the BIOS performs to check the RAM and keyboard?
3. If your computer is “hanging” and you click Restart, is this a cold boot or a warm boot?
4. Why does a computer still show the correct time after being unplugged for a week?
5. State two things you can change in the BIOS setup menu.

Assignment

In your notebook, write the five steps of the booting process in order, then give two differences between cold booting and warm booting.