i have some question about system BIOS


Mar 17, 2016
i read a lot of blogs and posts about this subject of bios and i still confused ,now i'm reading the book of a+ 901 902 (mike meyers)
so i find a lot of new information that i never learned.
so i will write my conclusion about this subject and i want to correct me if i'm wrong
so get the ball rolling:

the pc with cpu and other internel hardware is useless without a core programing that allow and enables the many different internel and external devices in a computer to function to together.

so in fact every device in the pc need a support programing that enable this device to communicat with cpu to do a certain funcation and this support programming is called bios so (there is a bios for keyboard controller and bios for hard drive, ..)

and all these bios together are called system bios that stored into Rom chip
so rom chip contains services(bios) that enable basic hardware to communicate with cpu

so my conclusion is that
bios is the name of services is not the name of all content of rom chip.. what i want to say is
rom chip contains the : --bios(services that enable the basic hardware to communicat with cpu )
-- in addition there is POST program that start when the cpu can communicat with basic hardware like keyboard controller that means when system bios is there after that pc starts the next program that's called POST to check the basic hardware like monitor or keyboard(in the POST not check the keyboard controller but keyboard itself)
--after POST process you can enter to another program called cmos utility or bios setup to change some data
--finally the boot process start

2- other thing, what i want to know is that if the bios /services that enables the basic hardware to communicate with cpu retrive or move to RAM when operating system is there (loaded) ?

finally i know i go deeply in this subject because i really want to build a strong base (to understand very well), because i know the fundemantls are very important if you want to continue in this field.

thank a lot


Limp Gawd
Aug 31, 2016
Bios - BIOS - Wikipedia, the free encyclopedia - Basic Input Output System

"The fundamental purposes of the BIOS in modern PCs are to initialize and test the system hardware components, and to load a boot loader or an operating system from a mass memory device. The BIOS additionally provides an abstraction layer for the hardware, i.e., a consistent way for application programs and operating systems to interact with the keyboard, display, and other input/output (I/O) devices. Variations in the system hardware are hidden by the BIOS from programs that use BIOS services instead of directly accessing the hardware. MS-DOS (PC DOS), which was the dominant PC operating system from the early 1980s until the mid-1990s, relied on BIOS services for disk, keyboard, and text display functions. MS Windows NT, Linux, and other protected mode operating systems in general ignore the abstraction layer provided by the BIOS and do not use it after loading, instead accessing the hardware components directly.

Most BIOS implementations are specifically designed to work with a particular computer or motherboard model, by interfacing with various devices that make up the complementary system chipset. Originally, BIOS firmware was stored in a ROM chip on the PC motherboard; in modern computer systems, the BIOS contents are stored on flash memory so it can be rewritten without removing the chip from the motherboard. This allows easy updates to the BIOS firmware so new features can be added or bugs can be fixed, but it also creates a possibility for the computer to become infected with BIOS rootkits."

You need to do a LOT more reading to understand how a motherboard works.