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What Is UEFI, and How Is It Different from BIOS?


Batu69

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New computers use UEFI firmware instead of the traditional BIOS. Both are low-level software that starts when you boot your PC before booting your operating system, but UEFI is a more modern solution, supporting larger hard drives, faster boot times, more security features, and—conveniently—graphics and mouse cursors.

 

We’ve seen newer PCs that ship with UEFI still refer to it as the “BIOS” to avoid confusing people who are used to a traditional PC BIOS. Even if your PC uses the term “BIOS”, modern PCs you buy today almost certainly ship with UEFI firmware instead of a BIOS.

 

What Is a BIOS?

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BIOS is short for Basic Input-Output system. It’s low-level software that resides in a chip on your computer’s motherboard. The BIOS loads when your computer starts up, and the BIOS is responsible for waking up your computer’s hardware components, ensures they’re functioning properly, and then runs the bootloader that boots Windows or whatever other operating system you have installed.

 

You can configure various settings in the BIOS setup screen. Settings like your computer’s hardware configuration, system time, and boot order are located here. You can access this screen by pressing a specific key—different on different computers, but often Esc, F2, F10, or Delete—while the computer boots. When you save a setting, it’s saved to the memory on your motherboard itself. When you boot your computer, the BIOS will configure your PC with the saved settings.

 

The BIOS goes through a POST, or Power-On Self Test, before booting your operating system. It checks to ensure your hardware configuration is valid and working properly. If something is wrong, you’ll see an error message or hear a cryptic series of beep codes. You’ll have to look up what different sequences of beeps mean in the computer’s manual.

 

When your computer boots—and after the POST finishes—the BIOS looks for a Master Boot Record, or MBR, stored on the boot device and uses it to launch the bootloader.

 

You may also see the acronym CMOS, which stands for Complementary Metal-Oxide-Semiconductor. This refers to the battery-backed memory where the BIOS stores various settings on the motherboard. It’s actually not accurate anymore, since this method has been replaced with flash memory (also referred to as EEPROM) in contemporary systems.

Why the BIOS Is Outdated

The BIOS has been around for a long time, and hasn’t evolved much. Even MS-DOS PCs released in the 1980s had a BIOS!

Of course, the BIOS has evolved and improved over time. Some extensions were developed, including ACPI, the Advanced Configuration and Power Interface.

 

This allows the BIOS to more easily configure devices and perform advanced power management functions, like sleep. But the BIOS hasn’t advanced and improved nearly as much as other PC technology has since the days of MS-DOS.

 

The traditional BIOS still has serious limitations. It can only boot from drives of 2.1 TB or less. 3 TB drives are now common, and a computer with a BIOS can’t boot from them. That limitation is due to the way the BIOS’s Master Boot Record system works.

 

The BIOS must run in 16-bit processor mode, and only has 1 MB of space to execute in. It has trouble initializing multiple hardware devices at once, which leads to a slower boot process when initializing all the hardware interfaces and devices on a modern PC.

 

The BIOS has needed replacement for a long time. Intel started work on the Extensible Firmware Interface (EFI) specification back in 1998. Apple chose EFI when it switched to the Intel architecture on its Macs in 2006, but other PC manufacturers didn’t follow.

 

In 2007, Intel, AMD, Microsoft, and PC manufacturers agreed on a new Unified Extensible Firmware Interface (UEFI) specification. This is an industry-wide standard managed by the Unified Extended Firmware Interface Forum, and isn’t solely driven by Intel. UEFI support was introduced to Windows with Windows Vista Service Pack 1 and Windows 7. The vast majority of computers you can buy today now use UEFI rather than a traditional BIOS.

How UEFI Replaces and Improves on the BIOS

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UEFI replaces the traditional BIOS on PCs. There’s no way to switch from BIOS to UEFI on an existing PC. You need to buy new hardware that supports and includes UEFI, as most new computers do. Most UEFI implementations provide BIOS emulation so you can choose to install and boot old operating systems that expect a BIOS instead of UEFI, so they’re backwards compatible.

 

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. It also boots in a more standardized way, launching EFI executables rather than running code from a drive’s master boot record.

 

UEFI can run in 32-bit or 64-bit mode and has more addressable address space than BIOS, which means your boot process is faster. It also means that UEFI setup screens can be slicker than BIOS settings screens, including graphics and mouse cursor support. However, this isn’t mandatory. Many PCs still ship with text-mode UEFI settings interfaces that look and work like an old BIOS setup screen.

 

UEFI is packed with other features. It supports Secure Boot, which means the operating system can be checked for validity to ensure no malware has tampered with the boot process. It can support networking features right in the UEFI firmware itself, which can aid in remote troubleshooting and configuration. With a traditional BIOS, you have to be sitting in front of a physical computer to configure it.

 

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.

How to Access UEFI Settings on Modern PCs

If you’re a normal PC user, switching to a computer with UEFI won’t be a noticeable change. Your new computer will boot up and shut down faster than it would have with a BIOS, and you can use drives of 2.2 TB or more in size.

 

If you need to access low-level settings, there may be a slight difference. You may need to access the UEFI settings screen through the Windows boot options menu rather than pressing a key while your computer starts. With PCs now booting so quickly, PC manufacturers don’t want to slow down the boot process by waiting to see if you press a key. However, we’ve also seen PCs with UEFI that allow you to access the BIOS in the same way, by pressing a key during the boot-up process.

 

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While UEFI is a big upgrade, it’s largely in the background. Most PC users will never notice—or need to care—that their new PCs use UEFI instead of a traditional BIOS. They’ll just work better and support more modern hardware and features.

 

For more detailed information, read Adam Williamson of Red Hat’s explanation of how the UEFI boot process is different. You can also read the official UEFI FAQ.

 

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In my opinion, the worst thing of UEFI is when I reinstall Windows, I need format all partitions on hard drive, not can only format OS partition. It makes me loosing all things on my machine!

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9 minutes ago, Error0101 said:

In my opinion, the worst thing of UEFI is when I reinstall Windows, I need format all partitions on hard drive, not can only format OS partition. It makes me loosing all things on my machine!

i don't know what do you mean, I never had that problem.

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43 minutes ago, Error0101 said:

In my opinion, the worst thing of UEFI is when I reinstall Windows, I need format all partitions on hard drive, not can only format OS partition. It makes me loosing all things on my machine!

that's why i keep everything my other OSes and files on other drives  away from windows say if reinstall  windows  all i have do is run a free program called DualBootRepair from Windows  and  it reinstalls grub boot menu  and i boot into windows anf Linux  with it instead of UEFI bootloader just like i never reinstalled windows. if you don't keep Linux on another drive it can  be a real pain if you use Windows 10 and you do upgrades every 6mths.   :)

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In my PC I have Windows XP and Windows 10. I need to change OS Entry Name of Windows XP from "Earlier version of Windows " to "Windows XP Professional". I have tried "DualBootPRO 1.1" and "EasyBCD 2.3.0.207". Both are not working properly. "DualBootPRO 1.1" has removed default Windows 10 Icon from graphical boot menu and "EasyBCD 2.3.0.207" has removed the completely graphical boot menu.

Can anyone confirm whether the "Visual BCD Editor" works perfectly or not?

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@hp owner Does this work for you?

personally I don't like to use Metro Bootloader.

FdJTOL5.png

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2 hours ago, BioHazard said:

i don't know what do you mean, I never had that problem.

Hi, all things I mean in this picture

UEFI-error.jpg

when I format old OS partition to make clean Windows install, If I use UEFI, I need to format all others partition. That makes all of my files gone

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@Error0101 oh i see, I never encounter that problem because I use GPT partition table.

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Just now, BioHazard said:

@Error0101 oh i see, I never encounter that problem because I use GPT partition table.

When you reinstall your Windows, do you format old OS partition?

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4 minutes ago, Error0101 said:

When you reinstall your Windows, do you format old OS partition?

I only format the os partition not any other partitions

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2 hours ago, Batu69 said:

That’s because UEFI uses the GPT partitioning scheme instead of MBR

Hi @BioHazard, when I reinstall Windows, if I need make a clean install, so I need format old OS partition. But during Windows install process, if I use default formatting tool, the tool will format old OS partion in MBR, so I cannot install new Windows on that MBR, then I need format all others partition, as result, I will loose all things on my hard drive. Hope you can understand what I said, sorry for bad English explain!

4 minutes ago, BioHazard said:

I only format the os partition not any other partitions

When you format your old OS partition, that partition did not revert to MBR? Why mine revert to MBR and it showed that Windows cannot install on MBR, and I need to format all others partitions, which contains my files

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Some Partition Mangers will let you convert MBR Partition Table to GPT .  Like PartitionGuru Free and others too

 

How to fix – The selected disk has an MBR partition table

http://www.eassos.com/blog/how-to-fix-the-selected-disk-has-an-mbr-partition-table/

 

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I think you better switch to GPT, I can format the os partition the rest of the partition will stay intact 

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Just now, steven36 said:

Some Partition Mangers will let you convert MBR Partition Table to GPT .  Like PartitionGuru Free and others too

 

How to fix – The selected disk has an MBR partition table


http://www.eassos.com/blog/how-to-fix-the-selected-disk-has-an-mbr-partition-table/

 

Hi @steven36, I know that. But how I can do when during Windows process and I've already format previous Windows partition? My problem is that

2 minutes ago, BioHazard said:

I think you better switch to GPT, I can format the os partition the rest of the partition will stay intact 

I mean I switch to GPT before, and I install Windows on UEFI mode. But when I reinstall Windows, and I format previous OS partition (which installing on UEFI mode as I said before), it revert my partition back to MBR, then show me that I cannot install Windows in UEFI mode on MBR disk. I need to format all others partition in MBR and install, so I lost all of my files on others partition.

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Just now, BioHazard said:

@Error0101 I don't know what to say as this never happened to me :think:

When you reinstall Windows, how you format your old Windows partition?

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Just now, Error0101 said:

When you reinstall Windows, how you format your old Windows partition?

I just use windows default format.

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20 minutes ago, Error0101 said:

Hi @steven36, I know that. But how I can do when during Windows process and I've already format previous Windows partition? My problem is that

Option 1 .It can be done with CMD while installing windows but also you  risk data lost

http://stepcoder.com/Articles/10067/convert-gpt-drive-into-mbr-using-command-prompt-cmd

Option 2:  it's more safer too do  it with a Partition manger. no data loss

http://www.thewindowsclub.com/convert-mbr-to-gpt-disk

Option 3:  Just put you're OSes on other drives  and back up your data and reformat the drive then and repair the boot loader.

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1 minute ago, BioHazard said:

I just use windows default format.

I also use Windows default format tool, but it revert me to MBR, and I cannot install Windows to that partition

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2 minutes ago, steven36 said:

Option 1 .It can be done with CMD while installing windows but also you  risk data lost


http://stepcoder.com/Articles/10067/convert-gpt-drive-into-mbr-using-command-prompt-cmd

Option 2:  it's more safer too do  it with a Partition manger. no data loss


http://www.thewindowsclub.com/convert-mbr-to-gpt-disk

Option 3:  Just put you're OSes on other drivers and repair the boot loader and back up your data and reformat the drive.

Option 2 is useless for me, because in my case, I'm on Windows install process, so I cannot go to Windows and formatting using Partition program. And Option 1 is also lost my data. Option 3 takes a lot of time. Anyway, thanks for your guide, but all things I've already known, and It still makes me crazy

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@Error0101 this is so weird and should never happen maybe try reset your uefi to default see if that works.

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Hi @steven36, I reinstall my Windows very often. I need find the way to give me easier process. Is there any way to format previous OS partition using default Windows format tool but still on GPT, not revert back to MBR?

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12 minutes ago, Error0101 said:

Option 3 takes a lot of time. Anyway, thanks for your guide, but all things I've already known, and It still makes me crazy

LOL for me i been using option 3 for years but i started using Linux in 2015  i just keep secure boot off . I keep all my Linux distros on a 1tb drives i keep all my portables ,installers .tuts and fixes on a 1 tb drive  and keep all my other Media on a 5 tb drive and I keep windows on  just a 150 gb drive lol. It don't take me but a minute  too repair the boot loader i just did it not long ago when i put windows 8.1 back in .

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@Error0101 I'm using UEFI. I always format OS partition during Windows Setup process and it never fails.

Do you use diskpart or Windows Setup to format your OS partition?

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rahuldohare
1 hour ago, Error0101 said:

Hi, all things I mean in this picture

UEFI-error.jpg

when I format old OS partition to make clean Windows install, If I use UEFI, I need to format all others partition. That makes all of my files gone

correct @Error0101 i face same problem when i format my pc.

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