THE TURM BIOS WAS CREATED BY GARY KILDALL and first appeared in the CP/M operating system in 1975 GARY KILDALL was one of the first people to see microprocessor as fully capable computers ,rather than equipment controllers and to organized a company around this concept .
Bios is BASIC INPUT/ OUTPUT SYSTYM ,the bios is the ROM chip found on motherboards that allow you to access and set up your computer system at the most basic level .
Ads by EonadsThe bios software has a numbers of different roles. But it most important role is to load the operating system. when you turn on your computer and the microprocessor tries to execute its first instructions, it has to get that instruction from somewhere, it cannot get it from the operating system is located on hard disk, and the microprocessor cannot get it without some instruction that tell it how, the bios provides those instructions, some of other common tasks that the bios performs.
When you turn on your computer, the BIOS does several things. This is its usual sequence:
1. Check the CMOS setup for custom settings
2. Load the interrupt handlers and device drivers
3. Initialize registers and power management
4. Perform the power –on self –test (POST)
5. Display system settings
6. Determine which devices ate bootable
7. Initiate the bootstrap sequence
The first thing the BIOS does is check the information stored in a tiny amount of RAM located on a complementary metal oxide semiconductor (CMOS) chip. the CMOS setup provides detailed information particular to your system and can be altered as your system changes l the BIOS uses this information to modify or supplement its default programming as needed .we will talk more about these settings later.
The bios has 4 main functions
POST
POST is a built - in diagnostic program. it is the set of routines stored in computer ROM .as the computer system is switched on, the POST has to make sure that all the hardware components such as RAM, the disk drives and keyboard are properly connected and the CPU and MEMORY functioning property if problems are found, these routines alerts the user either by sounding a series of beeps or by displaying a message, it is accompanied by a numeric value on the screen. if the POWER ON SELF TEST (POST) is successful, it passes the control to the system`s bootstrap loader.
The principal duties of the main bios during POST are as follows
§ Verify CPU registers
§ Verify the integrity of the BIOS code itself
§ Verify some basic components like DMA , timer interrupt controller
§ Find size and verify system main memory
§ Initialize BIOS
§ Pass control to other specialized extension BIOSes(if installed)
§ Identify organize and select which devices are available for booting.
BOOTSTRAP LOADER
Bootstrapping, boot loader or boot program a bootstrap loader, is a program that resides in the computer`s EPROM,ROM or another non volatile memory. it is automatically executed by the processor when turning on the computer . The bootstrap loader reads the hard drives. Boot sector to continue to load the computers operating system. The term, bootstrap comes from the old phrase “pull yourself up by your boot straps”
When the computer is turned on or restarted, the bootstrap loader first performs the power on self test.(post) if the post is successful and no issues are found, the bootstrap loader loads the operating system for the computer into memory the computer can then access , load , and run the operating system .
T he bootstrap loader was replaced in computers that have an EFI (extensible firmware interface) and is now part of the EFI bois.
BIOS DRIVERS
The BIOS `s first task is to configure all the system hardware with basic drivers so the system can get up and running. These drivers will set up and prepare the system memory and configure any peripheral devices for use such as the hard drives, optical drives, and video card. the BIOS loads a basic system that`s able to read the devices that contain the system operating system.
CMOS SETUP
CMOS is a type of memory technology , but most people use the term to refer to the chip that stores variable data for startup .A computer BIOS will initialize and control components like the floppy and hard drive controllers and the computer`s hardware clock , but the specific parameter for startup and initializing components are stored in the CMOS.
CMOS chips are desirable for battery –powered devices like laptops because they use less power than other types of chips. Although they use both negative polarity circuits(NMOS and PMOS), only one circuit type is powered on at a time .
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How important in bios in a computer system
The BIOS is the basic and essential portion of the motherboard firmware and is in charge of checking and booting the hardware attached to the device, there by passing the computer control to the operating system .It is most important part of the computer.
Computer and devices can not start without the BIOS
THE most important task the BIOS must handle ids making the transition from a mechanical , hardware gesture, like touching the power button to a more abstract level , like showing your operating system logo on the screen .this mean that when you power-up your system , the BIOS is the first program to run .its job is to start the coolers , check power levels, run some quick tests that evaluate the health of the system`s hardware and then load drivers and start the boot process for the operating system .if there is any failure during this process ,the BOIS displays a message informing you of what is wrong.
BIOS the operating system was the first software to run when a computer started. That meant that the computer could only run the built- in operating system.
HOW DOES THE BIOS WORK?
When the computer Is booted, the CPU activates the ROM BIOS chips. ROM BIOS then begins a series of system checks, called the power on self test (POST) . THE POST tells the CPU to check the bus (a series of connections that link all of the PC`s components) , the memory (RAM) the peripherals (keyboard, mouse.,etc) , and the disk drives. This system check is fast and not very thorough .the POST check is complete, the computer is ready to load the computer`s operating system. At this point, a user may notice that the light in drive a comes on again as the CPU checks to see whether a bootable disk has been placed in the drive. If it does not find the operating system software there, the CPU continuous to the hard drive, where it copies the operating system into memory so it is ready to go.
Configuring advanced BIOS may be dangerous if he user doesn`t know what every setting does and sets the wrong values, because the components of the system have limitations in the way they can be set. For example, asking the processor to work at a very high frequency cab make in overheat, throwing the computer into and endless restart loop. To make sure that you are safe, configure the BIOS settings only after consulting your system`s manual and be sure you know the capabilities of the hardware components you are setting.
Another job the BIOS have to deal with is to store these configuration settings when the system is powered off. to do this , it has a small amount of volatile CMOS memory that is powered by a battery like the one in the picture below . The term CMOS stands for complementary metal oxide semiconductor, representing the technological process used to make this memory chip. If the battery of the CMOS memory chip is dead and it can no longer provide energy, the BIOS will use the built – in default settings and not the custom settings you have set.
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WHAT IS THE DUAL BIOS?
The BIOS is located on the motherboard and it is a small read –only memory chip .the software on that memory chip is created by the manufacturer of the motherboard .if this memory chip fails, the BIOS cannot be loaded anymore, and the motherboard cannot be used .this is why motherboard use a DUAL – BIOS system on their modern motherboard. DUAL – BIOS means that there are two chips for storing the BIOS one for the main BIOS and one for a backup copy. if the main BIOS chip fails , you are asked to restart the computer and the backup BIOS chip is used to load the BIOS with the default settings . the BIOS includes on how to load basic computer hardware and includes a test referred to as a POST(power on self test) that helps verify the computer meets requirements to boot up properly . If the computer does not pass the POST, you will receive a combination of beeps indicating what is malfunctioning within the computer.
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