Firmware and BIOS/UEFI: The Program Inside the Device
You press the button and the computer comes alive. But before you see the desktop, one small program has already been working inside it — the firmware. Today you will follow the whole start-up, step by step.
For parents: a one-page guide — dinner questions and a “firmware hunt” at home.
01Remember
Think first, then open the answer.
What does a driver do?
It is a translator between a device and the system. The computer says what it wants, and the driver translates it into the device's language.
Which memory forgets everything when you switch the computer off — and which one keeps things?
Working memory (RAM) forgets without power. Storage keeps things even without power.
Why is it important to update programs?
Updates “plug holes”: they fix mistakes and weak spots. That is why we do them — but only from an official source.
02Story
For many years computers have had a small start-up program called BIOS (Basic Input/Output System). It comes from the design of the IBM PC. It was originally written in assembly language — a language close to the processor's own — for a 16-bit mode.
Over time that became too tight. So companies and developers joined together and created a new standard: UEFI (Unified Extensible Firmware Interface). It does the same job in a more modern way — it starts faster and supports bigger disks.
Today most new computers have UEFI. People still often say “BIOS” for both — and that is fine.
03Worked example
Firmware is a program stored inside the device itself — in memory that is not erased when the power is off. A computer has firmware. But so do a router, a TV and even some mice: they are small computers with a built-in program.
Here is what happens when you switch on a computer that runs Windows:
1 · Power
You press the button. Electricity flows to the motherboard.
2 · Firmware (UEFI / BIOS)
The first program to wake up. It lives in a chip on the motherboard and is ready before there is anything on the disk.
3 · Self-test (POST)
The firmware runs a power-on self-test and loads its own settings. It finishes when it finds a disk that has a system on it.
4 · Bootloader
A small program that finds the operating system on the disk and starts it. In Windows it is called Windows Boot Manager.
5 · Operating system
The system loads its core and the drivers it needs — those “translators” from the last lesson. Only then do you see the desktop.
04Try it now
1 · Predict
You switch the computer on. Which program starts first? Choose before you check.
2 · Run: the start-up step by step
This is a drawing of a screen, not a real computer. Press “Next step” and watch what appears.
3 · Change: what if the power goes out?
This is a drawing of a firmware update. First run it to the end. Then run it again and press “Cut the power”. What is different?
05No screen: “Firmware Hunt”
You need: a sheet of paper, a pen and an adult next to you. We only look — we touch and open nothing.
Walk around the home with the adult and look for devices that are small computers: a router, a TV, a wireless mouse or keyboard, a printer, a washing machine with a display.
Make a table with three columns: device · does it have a light, a screen or a menu? · I think it has firmware (yes / no / don't know).
At the end underline the three devices that surprised you most. Ask the adult: “Which of them updates itself, and which one only when we update it?”
06Make your own
Draw a 5-panel comic: “The Journey of a Start-up”. Each panel shows one step: power, firmware, self-test, bootloader, operating system.
- Invent characters. For example, a tiny alarm clock that wakes the machine.
- Add one sentence to each panel.
- Show the comic to someone at home and tell them where the firmware is.
07What I learned
- Firmware is a program inside the device. A computer has it, and so do a router, a TV and some mice.
- The start-up goes in order: power → firmware → self-test → bootloader → operating system.
- BIOS is the old name, UEFI is the modern successor.
- Firmware is updated only by an adult, from an official source — and the power is never cut.
A computer is not ready the second you switch it on — first it checks itself. What do you do in the morning before you are ready for the day?
Check yourself
1. Which program wakes up first after the button?
2. What does the bootloader do?
3. What is right when firmware is updated?
It is yours when you can put the five steps in order and explain to someone what firmware is. No points and no rankings — just a skill.
08I have a question
Do you still have a question? Write it here. It goes to your parent, not to strangers. Your parent confirms their e-mail first.
The form is loading… If it does not appear, write your question on paper and show it to a parent or teacher.
·Sources
- Title: Firmware and BIOS/UEFI: The Program Inside the Device (DB-RK-11) · Author: Children's Library, East Accelerator Foundation · Source: original content, 2026 · Rights: CC BY-SA 4.0.
- The facts were checked online on 02.10.2026 and put in our own words (links only):
- UEFI Forum: UEFI FAQs — what UEFI is and how it differs from BIOS.
- Microsoft Learn: Advanced troubleshooting for Windows startup issues (self-test, Boot Manager, loader, kernel) · UEFI firmware requirements · Secure the Windows boot process.
- Dell Technologies: How to Update BIOS — stable power; a failed update can damage the motherboard.
- NIST: glossary — firmware · Logitech: Firmware Update Guide — some mice and keyboards receive firmware updates.
- Product names (Windows, Microsoft, Dell, Logitech) belong to their owners and are used only to name the source.
- Licence: CC BY-SA 4.0 · Children's Library, East Accelerator Foundation, 2026. You may share and adapt this lesson if you credit the author and keep the same licence. Learning is free forever.