How a computer boots?

Installing an operating system

When you turn on your computer, it goes through a boot process to load the operating system and get ready for use. Here’s what happens:

1. First, the computer checks that all its attached hardware is working properly with a power-on self-test (POST), which is performed by the BIOS (Basic Input Output System) or UEFI (Unified Extensible Firmware Interface). BIOS and UEFI are software installed on the CMOS Chip (Complementary Metal-Oxide Semiconductor) of the motherboard.
2. The computer loads the bootloader from the MBR (Master Boot Record) of the boot device (i.e. an HDD, SDD or USB).
3. Then, the bootloader starts the operating system kernel.
4. The kernel gets the operating system ready to go and starts system services and processes.
5. Finally, the operating system loads the user interface, which lets you interact with the computer.

After the boot process finishes, your computer is ready for you to use and run applications. The exact steps in the boot process might be different depending on your hardware and operating system.

For instance, consider a scenario where you have a computer equipped with UEFI, a new solid-state drive (SSD) for storage, and you want to install the latest version of Windows, which at the time being is Windows 11.

In this case, the first step is to download the official ISO file from Microsoft website. The ISO file is an image of the Windows installation media, and it can be used to create bootable USBs or DVDs. To create a bootable USB, you can use a tool like Rufus. Rufus is a free, open-source utility that lets you create bootable USB drives from ISO files. It is simple to use and is widely considered one of the best tools for creating bootable USB drives.

Once you select the ISO file, Rufus will recommend using the GPT (GUID Partition Table) as the partition table. This is the default partition table used on UEFI systems. Rufus also sets up the target system as GPT (non-CSM), which means it disables the Compatibility Support Module (CSM). This is a component of the UEFI firmware that helps provide compatibility with legacy BIOS systems. Keep in mind that the default settings may vary depending on the operating system in the ISO file, and it’s important to ensure your target computer supports these settings before proceeding.

To finish creating the bootable installation device, simply select the device (e.g. USB drive) that you want to use as the bootable installation device, and then click on the “Start” button.

Great, now it’s time to boot from the USB. Before continuing, you’ll need to turn on your computer and access the UEFI boot menu to select your bootable USB. To do this, you may need to refer to the instructions for your specific computer model. On some systems, you can access the boot menu by pressing a specific key, such as F9, after pressing the power button. Once you’ve accessed the boot menu, select the USB that you inserted and it will load a mini operating system called WinPE (Windows Preinstallation Environment). This will allow you to install the full version of Windows 11 on the SSD.

WinPE automatically brings up a graphical user interface (GUI) to assist you with all the steps of the installation and configuration process. It will help you create the necessary partitions on the internal drive. Once these partitions are set up properly, the operating system will be installed, and you’ll be ready to start using your new Windows 11 installation.

During the installation process, your new SSD will be initialized with the GPT partition table and three partitions will be created by default. These partitions include one for the bootloader (EFI System Partition), one for the kernel and operating system (Basic Data Partition), and one for the recovery partition.

The recovery partition is a helpful feature on your computer’s hard drive that stores important information and files related to system recovery. It is usually created when you install the operating system and contains copies of the operating system files and other data that can be used to restore your system to its original state if something goes wrong. It’s important to note that the recovery partition is usually hidden and is not meant to be accessed or modified by the user. Instead, it is used by the operating system’s recovery tools to help you restore your system to a stable state in case of an issue. Some operating systems, such as Windows, also have tools that allow you to access the recovery partition and use it for tasks like creating a system restore point or restoring the system to its original factory settings.

It’s important to carefully plan your partition layout to ensure that you have enough space for all of your files and that the partitions are organized in a way that makes it easy to manage your data.

Conclusion

The boot process allows you to start or install operating systems from different drives such as HDDs, SSDs, USBs, SD Cards, CDs, DVDs, Network Drives, etc.

Installing an operating system involves copying the necessary files to your hard drive in a way that allows your computer to access and read them in the correct order to successfully boot the operating system. This process typically involves creating partitions on the hard drive and copying the corresponding files to those partitions. Once the installation is complete, you’ll be able to start using the new operating system on your computer.

There are two main types of partition tables that are used to organize the hard drive on a computer: the Master Boot Record (MBR) and the GUID Partition Table (GPT). The MBR is a legacy partition table format that was used by some older operating systems. It allows for a maximum of four primary partitions. On the other hand, the GPT is a newer partition table format that is used by many modern operating systems. It can support a much larger number of primary partitions and is generally more flexible than the old MBR format. It’s important to choose the right partition table format for your needs, as it can affect the performance and stability of your operating system.

Links:

• Rufus.
• Windows 11 ISO file.