BIOS vs UEFI
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UEFI and BIOS are used to boot computer system. Although UEFI is a newer software solution, it is not always necessary to use UEFI.
Some mother board provides led or bottom-right corner on monitor to display boot code status
| BIOS (Basic Input/Output System) | UEFI (Unified Extensible Firmware Interface)[1] | |
|---|---|---|
| Release Date | 1975. | 2002. |
| Operating Mode | 16-bit. | 32-bit/64-bit. |
| User Interface | Basic UI navigation using the keyboard. | Provides a user-friendly graphical UI with mouse support. |
| Partition Support | Up to four physical partitions. | Up to 128 physical partitions by using GPT partitioning scheme |
| Partition Size Limit | 2 TB. | 18 exabytes (~18.8 million terabytes). |
| Performance | Performs best on older 16-bit systems. | Faster boot time and better performance compared to BIOS. |
| Storage | System initialization information stored in a dedicated chip on the motherboard. | System initialization information stored in a .efi file on the hard drive. which is kept on a special disk partition called the EFI System Partition (ESP) |
| Security | Password protection | Secure Boot feature preventing unauthorized apps from booting |
| Pros and Cons | dual booting is much simpler | allows to utilize the UEFI shell environment |
| Boot process | power on
CPU starts up from BIOS firmware (POST) looks for a boot-loader (MBR) loads the kernel |
power on
CPU starts up from UEFI looks for a boot-loader (GPT) loads the kernel |
| CSM mode | UEFI firmware supports booting in legacy BIOS mode -Compatibility Support Module (CSM) - that provides legacy BIOS compatibility.
booting legacy BIOS-based systems from GPT disks is also possible | |
| Notes | Intel made the announcement in 2017 that by 2020 all CSM Modes in its Intel Motherboard's BIOSes will be removed. | UEFI classes
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