UEFI
In this video from ITFreeTraining I will look at Unified Extensible Firmware Interface or UEFI. Traditionally BIOS performed the role of the initial boot process for a computer; UEFI is replacing BIOS and addresses a number of limitations of the BIOS.
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What is UEFI?
0:0:17 UEFI was first developed in 2005. It was designed to replace BIOS. BIOS or the Basic Input Output System has been around since the 70s. There have been a lot of improvements in computing during this time and BIOS has been able to address some of these but not others. UEFI addresses the limitations of BIOS and also adds additional features that were not available in BIOS. The UEFI is a single chip located on the motherboard. You can see in this example, the left motherboard has one UEFI chip and the right motherboard has two. In the case of the right motherboard there are two chips in case one was to fail. The chip can vary in size and shape but generally nowadays is quite small. The UEFI chip contains the software that is used when the computer first starts up. You may also hear it referred to as firmware or even BIOS. Often hardware devices will have software embedded in them which is used to operate the device. For example, a video camera. Think of it as software for hardware. This software for hardware is often referred to as firmware. As the UEFI is software to make the hardware of the computer operate, this is why it is often called firmware. You may also hear UEFI referred to as BIOS. Whilst technically this is incorrect, BIOS has been around for so long that people, especially IT technicians, are just more accustomed to using this name. It may also be called UEFI BIOS. Next, I will take a look at some of the differences between UEFI and BIOS.
UEFI Direct Architecture Support
0:1:53 The first big difference is that BIOS supports only 16bit instructions, regardless of what the CPU supports. UEFI supports the same instructions as the CPU. CPUs on the market today are generally 32bit or 64bit. Since the first Intel CPUs ran in 16bit mode, it made sense for the BIOS to operate on 16bit instructions. However, as CPU’s improved, for backward compatibility reasons, BIOS kept running in 16bit. For a long time, since the BIOS was used for initial start-up and setup this was not a problem. With modern 32bit and 64bit CPUs, the CPU will start in pseudo 16bit mode. This mode allows the BIOS to operate with 16bit instructions. This has a lot of limitations, for example the BIOS will not be able to access all the memory in the computer. The idea behind having a pseudo 16bit mode is to allow BIOS to start the computer up and then switch to either 32 or 64bit mode. Thus, 16bit is designed essentially just to allow the operating system to boot and is very limited in what it can do. UEFI on the other hand, can run code that is the same as the CPU. This allows UEFI to access all the RAM on the computer. UEFI can also run its own software and device drivers without an operating system being installed.
Larger Storage Support
0:3:20 The next big difference is that UEFI supports larger storage devices. UEFI supports storage devices over two terabytes in size. It does this by using the GUID Partition Table or GPT partition table. BIOS uses a master boot record or MBR. MBR has the greatest compatibility since it has been around since the first personal computers were developed. However, MBR has a limit of only being able to address two terabytes of space. You will find however, that some operating systems and BIOS combinations will be able to use GPT drives as data drives and in some cases may be able to boot from them. The difference with UEFI is that it will always support booting from a drive with GPT. BIOS will not always support booting from a GPT drive, it depends on which operating system is running. Linux will generally support it whereas Windows will generally not. Most UEFI will also have backward compatibility options. These options will allow UEFI to use a storage device with an MBR partition.
Description too long for KZfaq. Please see the following link for the rest of the description. Access the rest of the course: ITFreeTraining.com/ap/1115
References
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Credits
Trainer: Austin Mason ITFreeTraining.com
Voice Talent: HP Lewis hplewis.com
Quality Assurance: Brett Batson www.pbb-proofreading.uk