uefi vs bios

StalePie42 · January 11, 2022

Hello, I just wanted to ask what is the difference between bios and uefi i understand that bios is a low level program in your motherboard that you can access by pressing delete key but i have no idea what uefi is or how to access it. Is there any advantage to using uefi?

thanks

GuiltySpark_ · January 11, 2022

If you have a system made in the last few years you likely have a UEFI and not a BIOS. Its accessed the same way in most instances, just hit Del repeatedly during the boot process. Confusingly to some, in common conversation, many still refer to the pre-boot UEFI environment as the "BIOS" as its just a simple term and most people know what you mean.

What system do you have?

Further reading: https://www.howtogeek.com/56958/htg-explains-how-uefi-will-replace-the-bios/

Kaaverik · January 11, 2022

UEFI will normally look a lot better than a BIOS. That is the usual way to tell it apart. BIOS and UEFI perform the same tasks on startup and initialization of devices in your computer, but the UEFI is the newer and better version. Almost all modern GPUs and systems come with UEFI standard because without it, the GPUs would not run (see number 3 below)

There is plenty of information that can be found here: UEFI vs BIOS: What's the Difference? (freecodecamp.org)

UEFI stands for Unified Extensible Firmware Interface. It does the same job as a BIOS, but with one basic difference: it stores all data about initialization and startup in an .efi file, instead of storing it on the firmware.

This .efi file is stored on a special partition called EFI System Partition (ESP) on the hard disk. This ESP partition also contains the bootloader.

UEFI was designed to overcome many limitations of the old BIOS, including:

1. UEFI supports drive sizes upto 9 zettabytes, whereas BIOS only supports 2.2 terabytes.

2. UEFI provides faster boot time.

3. UEFI has discrete driver support, while BIOS has driver support stored in its ROM, so updating BIOS firmware is a bit difficult.

4. UEFI offers security like "Secure Boot", which prevents the computer from booting from unauthorized/unsigned applications. This helps in preventing rootkits, but also hampers dual-booting, as it treats other OS as unsigned applications. Currently, only Windows and Ubuntu are signed OS (let me know if I am wrong).

5. UEFI runs in 32bit or 64bit mode, whereas BIOS runs in 16bit mode. So UEFI is able to provide a GUI (navigation with mouse) as opposed to BIOS which allows navigation only using the keyboard.