BIOS,

BIOS,

BIOS:

BIOS (Basic Input Output System) is a set of instructions or a small program stored in a chip in the motherboard of the computer, used to perform hardware initialization during the booting process (power-on startup), and to provide runtime services for operating systems and programs. 

As you know the main computer memory doesn't hold data when the computer is turned off, and on the other hand the computer needs a program to be useful which is the operating system that is stored in the hard disk, so one of the rules of the BIOS is to load the operating system and to initialize the hardware. 

Some of common tasks that the BIOS performs :

• A power-on self-test (POST) : a test of all the components to make sure everything is alright.
• Activating other BIOS chips on different cards installed in the computer - For example, SCSI and graphics cards often have their own BIOS chips.
• Providing a set of low-level routines that the operating system uses to interface to different hardware devices - It is these routines that give the BIOS its name. They manage things like the keyboard, the screen, and the serial and parallel ports, especially when the computer is booting.
• configure the hardware such as processor, RAM frequency...etc
• find a bootable device that the computer will use to boot, usually it contains an operating system and is the main hard disk of the computer or an operating system installer contained either in a DVD or a USB drive. 

 CMOS: 

when we define the BIOS we said that it configures hardware and looks for a bootable device, but where does it find the hardware parameters that will use to configure the hardware with, and what is the sequence of bootable devices it will follow? those informations and more are stored in a special chip memory called CMOS (complementary metal-oxide-semiconductor) it's not a volatile memory since it keeps data even when the computer is turned off it uses a battery for that, but what happens when the battery just died ? are its information lost? the answer is yes and no at the same time (this is not a puzzle to solve), it holds the default information stored there and it loses the change that had been made to them, for example: if someone changed the boot order of the computer to DVD first and the default setting was Hard disk so the setting will be hard drive since it's the default one, or if someone changed some RAM parameters they will be lost and the BIOS will use the default RAM settings during the boot.

Note that the settings you're allowed to change are defined by the setup program which will see later in this course.

when the battery of the CMOS died, you'll see a message whenever the computer is turned on informing you that the default settings will be restored.

The CMOS battery is used to keep the system time, this is why the time and date of your computer is correct (supposing of course it was correct the last time the computer was on and no one messed with the battery) when you turn on you computer, and when the battery dies you have to set the time every time you turn the computer on.

The Setup program: 

now suppose you want to change some hardware parameters or the boot order of your computer, how can you access the informations stored in the CMOS in order for the BIOS to use the modified parameters?

the answer is through the SETUP program of the motherboard. 

so the setup program is a built-in program used to configure the CMOS data and set the computer time.

How to access the Setup program?

usually when the computer is turn on you see something written at the bottom of the screen telling you the keyboard key you should hit to enter the setup, sometimes you don't see anything.

• For the desktop computers most of them use the delete key or F2 key.
• For laptops F2, sometimes F5, F6, F10, F12, and sometimes you have to use both Fn and one of the above keys.

If none of the above keys work just keep trying every function key or do a google search.

what can you do in the setup program?

Usually one access the setup program mostly to change the boot order to install an operating system, however there are many things you can change there and a lot of information about the system can be found there:

• Find out how much RAM the system has.
• Find out the capacity and number of the hard drives installed.
• Find out the system temperature along with the CPU temperature which is a racial information in case of a heating problem.
• Activate or disactivate some motherboard features such as USB.  
• Set the system time.
• Change the boot order.
• Change the voltages and frequencies of the CPU, though you have to be an expert to do so.
• Overclocking your CPU ,which is a feature to make it faster, but you have to consider the heating and power factors while doing that.
• Change the hard disk parameters
• ...etc

Notice that the things you're allowed to do is determined by the motherboard manufacturer so might find a lot of differences between the computers and the more setup programs you practice with the better for you.

Computer POST and beep codes:

The POST (Power-On Self Test) is the BIOS tests that performs on the hardware computer to make sure  everything is alright, however if finds something wrong it sends an error message through beeps, each BIOS manufacturer has its own beep code, the beep or beeps tell you what's going wrong with your computer, so you have to get a list of the beep codes of your computer to know the error and fix it. 

click here to get a list of the most common BIOS. 

How to check what BIOS you have and the version: 

- You can find out what BIOS you have by using this command in the command prompt : wmic bios get smbiosbiosversion (you can open the command prompt by clicking start and then run then type cmd).

- You can also find out the BIOS you have and the version by reading on the top of the first screen you have to read fast because it doesn't stay displayed long.

- And finally you can find out your BIOS version in the setup program, dependent on the setup you have you might click help or about or whatever. 

BIOS update: 

The BIOS might be updated to get the improvements released by the manufacturer, BIOS updates typically have very short change logs – they may fix a bug with an obscure piece of hardware or add support for a new model of CPU. sometimes people do a DOWNGRADE to their BIOSes to make them compatible with windows XP for example (some people like the past more than the future) because they have softwares that work only under windows XP   .

here is a video on how to update the BIOS:

UEFI:

The BIOS has been used for so long and has some limitations such as its vulnerability, some malicious programs use the BIOS to do their harm, and so the motherboard manufacturers fix them with the UEFI.

the UEFI is the modern BIOS if you want to, it fixed the issues of the BIOS such as:

• UEFI fixed the vulnerability of the BIOS by introducing the boot secure notion, which prevents anything from executing except the operating system installed.
• Hard disk with more than 2.2 Terabyte are not recognizable with BIOS and the UEFI fixed this issue too.
• The maximum number of primary partitions is 4 in the BIOS and is 128 in the UEFI.       

all the modern computers come with the UEFI, usually the UEFI has an attracting setup program that uses the mouse to navigate although it's not a rule.