The Differences Between BIOS and UEFI
When talking about BIOS or UEFI, both refer to the firmware responsible for ensuring that the computer boots up correctly. The question is, what distinguishes UEFI from BIOS? Especially with Windows 8, UEFI (Unified Extensible Firmware Interface) became widespread as Microsoft mandated its implementation on all new computers. BIOS and UEFI have many differences but also share some similarities. UEFI can also be installed on older computers if desired.
BIOS
BIOS stands for Basic Input Output System and is the predecessor of UEFI. BIOS primarily performs two tasks. One is to ensure a smooth computer startup. To achieve this, a small piece of software is loaded from a non-volatile memory on the motherboard, which enables the actual booting of the operating system. This process is known as "Bootstrapping."
The second task is to initialize all the hardware required for booting during the computer startup. This ensures that all components (CPU, GPU, hard drives, etc.) function properly when the computer starts up, allowing you to use the system. It also enables the installation of multiple operating systems using a bootloader, allowing you to choose between them during startup.
However, BIOS has some limitations. It supports only up to 2 TB hard drives and can only operate in 16-bit mode, limiting speed and functionality. The user interface is text-based and can only be navigated using the keyboard.
UEFI
The successor to BIOS functions similarly but offers numerous improvements. These include a graphical upgrade to the firmware and the ability to operate it using a mouse. Additionally, UEFI is much faster in terms of hardware initialization, resulting in a quicker system startup.
A significant advantage of UEFI is its support for hard drives larger than 2 TB, thanks to the GUID Partition Table (GPT). UEFI can also operate in 32- or 64-bit mode, allowing for more efficient use of hardware.
Moreover, UEFI includes network drivers, allowing the computer to boot over a network. It also features USB drivers (2.0, 3.0, and newer) to flash or reinstall UEFI via a USB stick without needing an operating system installed. This means that mouse and keyboard are fully usable and hot-pluggable.
UEFI also includes a boot manager, where you can set the boot order or exclude specific drives from booting. The new partitioning scheme, known as GUID, allows formatting hard drives larger than 2 TB. Additionally, individual drivers can now be disabled independently to isolate and troubleshoot PC issues.
Secure Boot
With version 2.3.1 of UEFI, the Secure Boot feature was introduced to prevent malware from installing into the bootloader. Secure Boot acts as a key, part of the bootloader, posing a significant challenge for software vendors, as obtaining a Secure Boot key is not straightforward. While it enhances system security, it significantly complicates the installation of bootloader software.
Secure Boot protects against bootkits and rootkits that infiltrate the boot process before the operating system starts. This is achieved by using signed bootloaders from trusted sources.
Recent Developments and Advantages
In recent years, UEFI has continued to evolve, now supporting the latest technologies like NVMe SSDs, which are significantly faster than traditional SATA SSDs. UEFI also improves energy efficiency with advanced power management features and supports modern security functions like Intel Boot Guard.
Furthermore, UEFI allows for quicker diagnosis and troubleshooting through integrated diagnostic tools and advanced logging features. This makes it easier for IT administrators and technicians to identify and fix issues without the need for extensive external tools.