Although the process is generally very fast, when you turn on a PC, a lot of things happen inside it before it is ready for use. All these things are part of the boot or boot process, short for bootstrap. The Boot or boot process of the computer is controlled by the BIOS which stands for " basic input-output system ", a software stored on a flash memory chip incorporated in the motherboard. In addition to controlling the boot process, the BIOS also offers a basic configuration interface for managing PC hardware components.
I have already talked about this extensively by explaining what the BIOS is for and what it does on a computer.
To open the BIOS software, simply press the key that is indicated as soon as you turn on the computer, where you should read, among the various writings on the black screen, something like " Press DEL to enter Setup Menu " (DEL would be the Del key ).
In another article, we explained all the ways to access the BIOS.
In modern computers the BIOS is an easier to understand and configure software called UEFI (Unified Extensible Firmware Interface).
READ ALSO: How to reduce BIOS and PC boot time
what happens when you turn on your PC
.The power button activates the PC power supply, sending power to the motherboard and other components.
The PC performs a power-on self-test through an operation called POST (Power-on self-test).
POST is a small computer program within the BIOS that checks for hardware failures.
POST makes a single beep sound if all goes well while other sequences of beeps signal a hardware failure that repair specialists can interpret to understand what's broken.
Note that in many PCs the POST is disabled or does not emit the acoustic signal when everything is fine.
When you turn on your computer, you can read boot data on the screen that indicates the type of BIOS, how to access the BIOS, how to access the boot menu, processor specifications, the amount of RAM installed and the drives detected.
In many PCs this information does not appear and is replaced by a screen showing the manufacturer's logo.
In the BIOS settings, you can still reactivate the POST screen, if you prefer.
After turning on the PC, the BIOS attempts to access the first sector of the disk or MBR designated as the boot disk.
The first sector is the first kilobyte of the disk and the unit is read sequentially starting from the first available memory address. The startup disk is typically the same hard drive or solid state drive that contains the operating system.
We have seen in another article how to change the computer boot disk by configuring the BIOS or interrupting the boot process with a sequence of keys (often indicated on the boot screens).
In that first sector of the boot disk, called the Master Boot Record or MBR, the boot loader is loaded into the PC's memory (RAM).
The boot loader is a small program designed to find and launch the PC operating system. Once the boot loader is in memory, the operating system starts loading. In Windows 10, the new, faster boot loader is based on the GUID Partition Table (GPT), although it is still using the older MBR.
READ ALSO: How to convert the disk to GPT and activate UEFI
If your computer fails to start before you even see the Windows logo, the most common causes are:
- The operating system is missing (perhaps because the boot disk was wrong);
- The bootloader is damaged (and we have seen how to restore the bootloader and MBR.
- RAM memory is damaged
- The computer fans are not working to cool the processor.
READ ALSO: How to turn on the PC if Windows does not start "> because a computer freezes or stops at startup
- What to do if Windows 8 does not start
- How to repair Windows 10
