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The Differences Between UEFI and BIOS

The first interaction with these two terms occurs when we need to change system settings of either a window or Mac PC. Mac uses UEFI while the windows uses BIOS system to start with. Both systems are firmware that are responsible to act as a middle language between the hardware language and the higher programming language like Windows OS or OS X (Mac).

The UEFI and BIOS firmware are relatively important in any system around because of intermediary features. They are the main interfaces of the computer world at the moment since the beginning and development of computer technology and they act as interpreters between the installed Operating Systems and computer firmware attached. It for this reason that they are a key element when one is operating a device.

They are similar in functionality in that they both are used in aiding the computer during start up to initialize the hardware installed and also help in starting up the pre-loaded Operating System. This is one of the few similarities that this two firmware may have but it should be noted that apart from the mentioned above function, they are different in many different ways as mentioned in the above article and keen interest is usually on the functions that they do and the design of the two firmware and how it affects the computer functioning in general.

Differences between UEFI and BIOS

Main Importance of This Firmware

So this firmware is very important and in case we have to change any system setting which is very crucial in the health and survival of the system, then we need to do it from inside, i.e. using the firmware inside. They are the main source of information and interaction between the user and the system as a whole. Another important role of such firmware is to boot the system initially. Yes, this is the program which is responsible for waking up your system and starting it, every time. It is entrusted with all the required data to help the computer during start up and link the hardware connected too to the computer. All these are done during the period a computer is booting.


So the difference between UEFI and BIOS is that the first one is used by OS X operating system while the second one is used by Microsoft’s Windows operating system. This is one of the major differences that can be noted when mentioning the differences between the two even without starting up the computer.

That was the initial difference between these two special programs. But, that’s not the only one! If you wish to continue learning about the differences between UEFI and BIOS in detail, then you should proceed ahead.

Before we take an in depth look at the major physical and software differences between the firmware, it is vital to mention the characteristics and discuss what they are. A brief discussion on what UEFI and BIOS are is provided below in order to understand where the differences come in in terms of their structure and design.

BIOS Firmware

BIOS (Basic Input/output System) is the oldest of them since it has been used since the 20th century and still widely used compared to UEFI which is more of a recent technological development. It is different in functioning from start up since it reads the initial/ first sector of the hard drive while it is having the next device address in its memory to initialize or a developed code to execute. It is also instrumental in selecting the boot device that is needed to initialize by the system from starting the Operating System.

UEFI Firmware

On the other hand, UEFI (Unified Extensible Firmware Interface) is used to conduct the same task as the BIOS but a little different in terms of its functioning. A unique feature it has is that it stores its information about initialization and start up in its .efi form instead of being stored in the firmware. It is usually stored in the hard drive inside a special partition (ESP). It also has a boot loader program that is used with the Operating System installed initially. In the recent past, UEFI is becoming more powerful compared to BIOS and it looks like it is totally set to replace BIOS in the future and bring in many feature with it that will provide enhancements that cannot be done or accommodated by the previous BIOS version.

As it is mentioned in the above article in detail, UEFI has a technical advantage over BIOS in so many ways but the BIOS has some limited advantages too that make it a little bit powerful than UEFI and the reason why some people are resisting towards changing to the trending UEFI firmware.

Just to mention a few of the technical advantages in point form is: –

  • Ability to boot from larger disks compared to BIOS
  • CPU independent architecture
  • CPU independent drivers
  • Flexible pre operating system environment
  • Modular design
  • Backward and forward compatibility

A look at an in depth comparison between the UEFI and BIOS systems is as discussed below as the major point.

Major Differences Between UEFI and BIOS Systems

#1 Performance

UEFI firmware uses a special firmware to store the boot files. This system is called EFI System Partition and the format in which files are stored is ‘.efi’. The same file is also responsible for holding the boot loader of the operating system. When it comes to advancement and technical benefits, UEFI is way better than BIOS.

On the other hand, BIOS uses the first sector/section of the main hard drive to store the initialization code and further execute it. The first partition of the hard drive holds the location/address of the code needed to initialize the system. BIOS is the older one between these two systems we have here for comparison and thus it has some limitations.

It still uses a 16 –bit architecture which holds it back from using a lot of codes to execute at a single time. Thus, the system is slower than the UEFI.

#2 Security

The second big difference comes at the security standard. UEFI system never allows any program to execute during the booting which doesn’t have authenticated drivers. A fancy term for this safe booting is ‘safe boot’.

In case of windows, i.e., the BIOS, it doesn’t have this special type of authentication facility which can allow any program to enter into the booting schedule. Thus, it is easier for malware to attack Windows system than Mac ones.

Recently, Microsoft implemented a Safe Boot feature in the Windows 8 OS, which is still continuing in OS versions launched after the 8. But, still it’s not that great as in the case of UEFI.

#3 Speed

Our UEFI system doesn’t depend on any platform, thus it always loads up files quickly and offers a better speed, comparatively. But, it isn’t true in every case. There are cases or situation where BIOS works faster than UEFI. So a better clarification here can be that if UEFI is well configured than it works faster than BIOS, otherwise not.

#4 Size Limitations

As I added above, BIOS uses a 16- bit architecture which holds it back in case of executing large size of the code. Technically, BIOS uses MBR (Master Boot Record) to store the information (code) and execute it from the hard drive.

On the other hand, UEFI uses GPT (GUID Partition Table) which is currently working on a 64 – bit architecture that can easily access and execute more code at a single time.

These are the major differences separating UEFI and BIOS systems as the difference is what that makes the UEFI firmware more popular among recent technologies.

Discussion On Some Minor Feature Differentiating UEFI and BIOS Systems

If we continue looking at some light differences between BIOS and UEFI, we get that BIOS was initial pre-installed on all motherboards from the past technologies and even some recent ones. One of the downfalls of BIOS firmware as versatile component in computer operation is the difficulty of use and also the technicality incurred when it comes to configuration of the computer systems due to its design.

Also BIOS has remained quite unchanged for a very long time compared to UEFI that despite being developed just the other day has undergone some system improvement generally and frequently. BIOS has become outdated in terms of its pre-installed software and generally unsupportive to the recent newly developed technologies around the world. This makes it an analog type of firmware.

How Is BIOS Advantageous Compared to UEFI Systems?

Despite all these downfalls of the BIOS system, it can be a handy tool in a number of situations where it has over power UEFI firmware. Some of the scenarios where BIOS is most preferred are: –

  • Since it is totally independent from the operating system it can be then accessed with no installed operating system required and minimum components to navigate and configure.
  • Advanced software users can also adjust different settings available in the BIOS menu with so much ease and few components like the clock speed, memory latency and several other setting options available in BIOS menu.
  • It also allows tweaking of a computer to achieve some optimum performances that couldn’t be achieved when one was using the UEFI firmware as a recent development.

But one thing that should be keenly headlined is that when it comes to using BIOS firmware and navigating in its menu to alter the system settings, it should preferably be done by a professional to avoid mistakes that may incur or permanent hardware damage due to lack of knowledge of how to go about malfunctioning of devices and the system.

How UEFI is superior to BIOS systems

When it comes to discussions about UEFI, it is known as an advanced technology developed by the Intel Company and has been gaining much required attention in the recent years and it is being adapted by computer manufactures recently in their systems. It has a unique legacy support that can house BIOS functions in it as an added advantage and other features that edged BIOS firmware.

Despite it superiority and complexity, it is somehow limited due to the processor architecture of different system. In a 64-bit processor it has full support of the UEFI systems while in the x86 processors it will have just partial or no support at all. This is one of the major limitations. Also the operating system must emulate a BIOS environment in order to function properly or it will make the installed extra components attached to it not to work totally.

It is because of this, it has forced microprocessor manufacturers and OS developers to work together to aid in eliminating these problems and try to succeed to some desired extent. Some of the known companies giving support to UEFI systems are Apple, Intel, AMD, Dell and many more. A company that a given full support to the UEFI technology is the Microsoft Company.

A major backslide of the BIOS systems is that it is totally limited to a 1MB memory with 16 Bit instruction option and (MBR) partitioning system which support only 2TB maximum of hard drive which is limited to only 4 partition options. This is a back slide with the need for flexibility due to developed technologies and also future ones.

UEFI as a powerful system has several advantages either major or minor ones: –

  • It has a modular design that can support 128 partitions and a staggering option of up to 8ZB of hard disk space with its installed GPT system.
  • It provides closer integration with the Operating System with the advanced start up options available.
  • To boost its security options, it has the secure boot feature readily installed.
  • A workaround of UEFI also allows users to manually add a new key to the database and install desired operating systems.
  • Another advantage that makes UEFI preferable is the ability to advance with new functionalities can be added as computer hardware advances generally. This makes it future proof.
  • UEFI is also a development with its user friendly interface that makes it totally easy to use compared to BIOS that is very difficult to navigate through and set up too.
  • A new development in the UEFI systems is that they have a specialized Graphic User Interface that can even be compatible with a mouse for navigation.
  • Also motherboard manufactures can implement different software modules available in UEFI systems which allow users to test installed components easily.

These are some of the features that UEFI comes with that make it a better option compared to BIOS systems generally from its modular design, architecture to its ease of use.

Wrap Up

Even if UEFI has more advantages than BIOS, it is still used in limited systems. While, BIOS is used in a wide variety of computing systems. The prime reason behind is because it supports very limited systems. Despite the many advantages that come with it, it will still take time to transit from BIOS system to UEFI system over the years. It will take some time to allow manufacturers to adopt the new system and enable the prices of UEFI motherboards to be lesser. Hence as much as we know it is a powerful system and is overtaking BIOS system, it will take time to be an industry standard.

So folks, how was this knowledge full guide? Was it helpful enough to offer you basic level of differences between UEFI and BIOS? If yes, then let me know which one is better and which one you should be using in future? Choose the one which is future safe and also have advancements in technology.

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