All About BIOS and UEFI Boot Managers: Disadvantages and Differences

The computerized devices we know today have a primary program in charge of making these devices work as the specs of their design.
In this perspective, a computer is conceptually an all-in-one, i.e. many independent, interconnected devices (graphic card, network card, mouse, printer, etc.) are there. They require some program for their integrated and proper working, which is called Firmware (BIOS and UEFI).

So in computers being a set of interconnected electronic devices, you need some program that takes control of those devices. IBM introduced something in 1980, calling it BIOS, which Would soon become a standard and has been used up to these days.

BIOS and UEFI are the necessary input and output systems. These small systems are in charge of starting the base firmware of our computer. Although roughly the purpose of both elements is the same, they are very different systems, as this article will explain.
New system manufacturers use UEFI firmware than old BIOS. Both of them starts when you boot your PC. But UEFI is a more advanced solution. It supports bigger hard drives, has faster boot times, and greater security features.

What is BIOS? What are its Functions and Limitations:

The BIOS (Basic Input and Output) is an essential software that in an integrated circuit independent of the motherboard and is accountable for starting the devices required for a computer to work normally.
The BIOS is responsible for low-level control of all hardware devices on the computer. Thanks to this software it is possible to load the operating system, stored on the disk, in the main memory so that any user can use the resources of the computer in a language of high level. It also enables you to alter certain parameters of your configuration, but since programming of BIOS is in the 16-bit environment, it has basic and limited interfaces.

BIOS setup utility

Primary functions of BIOS system includes:

  1. It keeps check and balance of each section of the RAM and makes sure that everything is running fine.
  2. Once it validates RAM and Processor, it continues to examine other connected devices like mouse, keyboard, printer, etc.
  3. After this, BIOS tests for the boot options of the OS.
  4. It organizes the various boot alternatives in a particular sequence as per their priority. You can see it in BIOS while booting. Boot options include Boot from CD-ROM, Boot from Hard Disk, boot from USB, etc.
  5. It then examines for the bootstraps on different devices in the fixed order.
  6. The BIOS also review the CMOS, and other chips to set the date/time on the system and it is also responsible for device driver loading.
  7. Once all of the above steps complete, it transfers the control to the OS by loading the main parts of it into the part of RAM.

Why UEFI is replacing BIOS???

It’s since ages when BIOS came into existence. And it has not grown much. Even PCs with MS-DOS had it!
It’s not like nothing has changed since the 80s, it has improved over time. Some extensions such as ACPI (Advanced Configuration and Power Interface) are there. This allows the BIOS to manage devices swiftly and offer advanced power management functions. But it fails to race with the advancement of computer technology since the days of MS-DOS.

The BIOS system has few serious limitations:

  1. It can boot from drives of less than 2 TB. 3+ TB drives are now standard, and a system with a BIOS can’t boot from them.
  2. The BIOS is comfortable running in 16-bit processor mode, and it has only one MB of space to execute.
  3. BIOS can perform through extinct MBR partitioning system, which is also outdated and replaced by GPT.
  4. It has trouble in initializing multiple devices in one go due to the small cache memory, so modern fast computer technology rejects it.

BIOS killer UEFI: Introduction and Advantages:

T o overcome all of the limitations of tradition one, in 2007 Intel, AMD, Microsoft, HP, etc. agreed to promote a new Firmware interface called as Unified Extensible Firmware Interface (UEFI). Specification managed by the Unified Extended Firmware Interface Forum. The vast majority of computers today use UEFI rather than traditional one.
UEFI systems are ready to work hand in hand with today’s new hardware. This type of systems can boot from hard disks up to 9.4 ZettaBytes (more than 10 billion Terabytes), size three times higher than it is believed to be able to occupy the Internet today. Also, it is compatible with the GPT partition tables, necessary to work with large hard disks.

UEFI is much more than a simple firmware upgrade of BIOS:

The UEFI is not only a replacement; you can call it a small operating system. The mouse can be used to control it. In some particular models, it is possible to even run other applications on it, For example, hardware diagnostic tools.
We can update it from the manufacturer site using the updating tool and also be using the software on the motherboard. we can even configure it, being very useful, for example, to Do overclocking tests without having to restart to make little improvements.

There are many ways to enter the UEFI of a system. We can enter it as we do for BIOS, however, if we have security options enabled to access, it must do so from the Options of “advanced restart” of our operating system.

Difference Between UEFI and BIOS:

There are many differences between BIOS and UEFI, few of them are:

  1. Its architecture, UEFI works natively with both 32 and 64 bits, unlike BIOS which works only with 16 bit systems.
  2. UEFI works with GPT partition table which is an advanced form of MBR. BIOS is compatible with MBR only. Further read: Difference between MBR and GPT systems
  3. Use of MBR partition table by BIOS restricts the total physical partitions to each of 2TB (maximum) in size whereas UEFI partition table (GPT) uses 64-bit entries in its table which lengthens the assistance for volume possibilities of the hard drive.
  4. Unlike BIOS, UEFI is independent of the motherboard; it may be capable of improving the boot time and speed of the system. It is good if you have large hard disks attached to your computer.
  5. Secure boot is a characteristic of UEFI that has been executed in Windows 8. The perk of UEFI is its security over the older one. UEFI allow only genuine drivers/services to load at startup, making sure that no ill program can load on startup. Microsoft using this feature to save itself from piracy. This secure boot characteristic is the cause why we get errors in installing new OS on the computer.
  6. The memory chip that includes UEFI is open on the board unlike BIOS, so we can add third-party extensions as tools for overclocking or diagnostic software.

difference bios and uefi boot process

Can I change my BIOS for a new UEFI????

Answer is NO!!!!!
If you still have a system with a traditional BIOS, there is no way to update to UEFI. Changing from one system to another is not like changing an operating system. We can download the newest version of the firmware for our board. This will remain same. Although it can correct errors and enhance the performance of the system, you will not be able to enjoy the new features of this new computer.

Any motherboard you buy today will already UEFI, and any hardware that you connect to it will be ready to boot into these systems. So assembly and start-up remain the same.

boot mode selection

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