Basic Input/Output System (BIOS) is a small piece of software. It is the lowest level of operating system that sit on ROM or flash memory chip on your computer motherboard. It is also referred to as motherboard firmware since it links the hardware to the software.
What BIOS actually does is that its initialize your devices accordingly CPU, RAM, Graphics Card, Peripherals and so on.
The BIOS first check the setting stored in a single Chip to determine how the user want the system to run. So that’s all the stuffs in the utility you get in b smashing one of the function keys, delete, Esc key when you first boot up.
The BIOS will then run Power On Self Test (POST) to ensure that all hardware in your computer are working perfectly well. It usually produce a beep sound provided that the laptop has internal speaker built in the PC to tell the user that the hardware are working fine otherwise the process will stoop if the part that failed is an essential part of the laptop ( the laptop needs that part to boot up ) or it drop a message on the screen to tell you the particular par that failed if its not an essential part of the laptop ( the laptop does not need the part to boot up ).
If everything goes well, the BIOS will check for any boot-able device meaning and kind of drives that have operating system on it and then hand off control of your computer to the OS
THE TYPES OF BIOS
The old school BIOS, often provide link between the keyboard, mouse and other devices and OS ( the BIOS serves as an interface between the hardware and software. While the modern Operating system for instance, the newer version of windows control the hardware more directly. So once you are at the windows desktop, the BIOS goes to rest until it is need again.
The way the BIOS was implemented for a long period of time had some limitations. Some of the most obvious of them are:
It does not support graphical interface. It just had a blue background and a text style menu.
The conventional BIOS uses driver support to access your hard drive called the “Master Boot Record” or MBR and it could only handle partition less than two
It is limited to four partition, meaning you can only create four partition. This conventional BIOS I just talked about now is called LEGACY BOOT. This was fine for a long time, but with many modern hard drives held way more data, it became obvious that something new was needed.
Then the "Unified Extensible Firmware Interface (UEFI)” was introduced. Not only the UEFI was able to overcome those limitations, it is also quicker than the Legacy Boot to boot up
On the UEFI you get an advanced graphics. UEFI setting are easy to set up. And if you have over two (2) terabyte that you want to boot directly from, UEFI is what you should probably use.
In the same vein, you probably want to use GPT. what does that means is that when you first plug in your drive, you get a message that says do you want to use GPT or MBR. If its large drive it needs to be GPT otherwise the largest partition you can make is two terabyte. So it is very important to know, If you do a GPT drive you will probably want to use UEFI. While if you do MBR drive, yo would want to use LEGACY BOOT. They both work together. In the BIOS Setting, make sure UEFI is enabled when use are using GPT and disable LEGACY BOOT and all options concerning LEGACY BOOT.