BIOS vs UEFI

BIOS

BIOS abbreviation Basic Input Output System, is a non-volatile firmware used to perform hardware initialization during the booting process of a computer. It provide runtime services for operating systems and programs. It also manages data flow between the computer's operating system and attached devices such as the hard disk, video adapter, keyboard, mouse and printer.

The name originates from the Basic Input/Output System used in the CP/M operating system in 1975. CP/M originally standing for Control Program/Monitor and later Control Program for Microcomputers that is a mass-market operating system created in 1974 for Intel 8080/85-based microcomputers. The term BIOS was created by Gary Kildall.

The BIOS includes instructions on how to load basic computer hardware and includes a test referred to as a POST (Power On Self Test) that helps verify the computer meets requirements to boot up properly. If the computer does not pass the POST, you will receive a combination of beeps indicating what is malfunctioning within the computer.

The BIOS firmware comes pre-installed on a personal computer's system board. BIOS is a program that is made accessible to the microprocessor on an erasable programmable read-only memory chip. When you turn on your computer, the microprocessor passes controlto the BIOS program, which is always located at the same place onEPROM.

When BIOS boots up your computer, it first determines whether all of the attachments are in place and operational and then it loads the operating system into your computer's random access memory from your hard disk or diskette drive.

BIOS boots by reading the first sector on a hard disk and executing it,this boot sector in turn locates and runs additional code. The BIOS system is very limiting because of space constraints and because BIOS runs 16-bit code, whereas modern computers use 32-bit or 64-bit CPUs.

In October 2017, Intel announced that it would remove BIOS support from all its products by 2020, in favor of UEFI Class 3.

UEFI

Unified Extensible Firmware Interface in short UEFI, is low-level software that starts when you boot your PC before booting your operating system like BIOS. But UEFI is a more modern solution, supporting larger hard drives, faster boot times, more security features, and conveniently graphics and mouse cursors.

Tiano was the first open source UEFI implementation and was released by Intel in 2004. Tiano has since then been superseded by EDK and EDK2 and is now maintained by the TianoCore community.

The original motivation for EFI came during early development of the first Intel–HP Itanium systems in the mid-1990s.

In July 2005, Intel ceased its development of the EFI specification at version 1.10 and contributed it to the Unified EFI Forum, which has developed the specification as the Unified Extensible Firmware Interface (UEFI). The original EFI specification remains owned by Intel, which exclusively provides licenses for EFI-based products, but the UEFI specification is owned by the UEFI Forum.

In December 2018, Microsoft announced Project Mu, a fork of TianoCore EDK2 used in Microsoft Surface and Hyper-V products.

Like BIOS, UEFI is installed at the time of manufacturing and is the first program that runs when a computer is turned on. It checks to see what hardware components the computing device has, wakes the components up and hands them over to the operating system.

By contrast, UEFI boots by loading EFI program files from a partition on the hard disk, known as the EFI System Partition (ESP). These EFI boot loader programs can take advantage of EFI boot services for things like reading files from the hard disk.

This new standard avoids the limitations of the BIOS. The UEFI firmware can boot from drives of 2.2 TB or larger, in fact, the theoretical limit is 9.4 zettabytes. That's roughly three times the estimated size of all the data on the Internet. That's because UEFI uses the GPT partitioning scheme instead of MBR.

UEFI supports a feature called Secure Boot that's intended, as the name suggests, to improve security. It does this by requiring a digital "signature" of boot loaders, which in turn should require signing of kernels, and so on up the chain. This should make it harder for malware authors to insert their code into the pre-boot process, thus improving security.

It’s not just a BIOS replacement, either. UEFI is essentially a tiny operating system that runs on top of the PC’s firmware, and it can do a lot more than a BIOS. It may be stored in flash memory on the motherboard, or it may be loaded from a hard drive or network share at boot.

Different PCs with UEFI will have different interfaces and features. It's all up to your PC manufacturer, but the basics will be the same on each PC.

BIOS vs UEFI

• BIOS uses the Master Boot Record (MBR) to save information about the hard drive data while UEFI uses the GUID partition table (GPT).

• Since UEFI is platform independent, it may be able to enhance the boot time and speed of the computer. This is especially the case when you have large hard drives installed on your computer.

• Secure boot is a feature of UEFI that has been implemented in Windows 8 recently. The biggest benefit of UEFI is its security over BIOS. Secure Boot works by requiring a digital signature of boot loaders which should require digital signature by the Kernel.

• Under the hood, the UEFI code runs in 32 or 64 bits, while the BIOS usually does it in 16 bits.

• BIOS can be used in devices that do not require large storage or security.

• Every motherboard has a BIOS which can be handy in a number of situations.

• Users can access the BIOS with no operating system installed and with a minimum of components.

• The memory chip in which the UEFI is installed is not blocked on the motherboard as BIOS.
  

• UEFI has more advanced features than BIOS in order to pair with the latest hardware improvement.

• The BIOS has a very MS-DOS design, and you can only move through it using the keyboard. The UEFI instead has a much more modern interface, allows you to include animations and sounds, and allows you to use the mouse to interact with it.

• The boot of the computer is faster with UEFI than it was with BIOS.