b.i.o.s
DESCRIPTION
Basic Input Output System. B.I.O.S. Plan of the presentation. Introduction Presentation History BIOS: a hardware A component A storage space Evolutionarity BIOS: a firmware BIOS an algorithm Hardware management An interface Starting diagram Future. Introduction. Presentation - PowerPoint PPT PresentationTRANSCRIPT
Plan of the presentation Introduction
Presentation History
BIOS: a hardware A component A storage space Evolutionarity
BIOS: a firmware BIOS an algorithm Hardware management An interface Starting diagram
Future
Presentation Basic Input Output System ou BIOS
package of basic function (read, write, …)
contents in the read-only memory (ROM) of the motherboard
Term used for the whole of the “firmware” or “microcodes” of a motherboard
Intermediary between the Hardware and the Operating System
History 1981 : program code that makes up the BIOS
Before the 90s so BIOSes were held on ROM chips
○ could not be altered○ As its complexity and need for updates grew
Between 90s and 2005 BIOS firmware was subsequently stored on EEPROM or flash memory
In 2006, the first systems supporting a Serial Peripheral Interface appeared, and the BIOS flash moved again
In the newest systems, the core of this code remains functionally identical to that in decades-old machines
A component type of component: CMOS
Particularity: low energy consumption
Directly implant on a motherboard or a peripheric card
ROM (90s)
○ Manufactured by the designer of Mother-Board
○ Can’t be altered
PROM / EPROM / EEPROM (90 to Nowadays)
○ A first version was implement in
○ Manufacture release update
○ Can be update
Supplied with a battery (lithium) Save personnal change (except Rom)
A storage space BIOS is a storage space:
stored in a permanent way○ lithium battery○ low energy consumption
a memory of reduced size○ No more than 100 bytes
contains:○ parameters○ functions
Evolutionarity computer system can contain several BIOS firmware chips
plug-in adapter cards such as SCSI, RAID, Network interface cards, and video boards include their own BIOS
Add-in cards usually only require such an add-in BIOS if they: Need to be used prior to the time that the operating
system loads Are not sufficiently simple, or generic in operation to be
handled by the main BIOS directly
Evolutionarity
Older operating systems such as DOS may continue to ake use of the BIOS to handle input and output
most modern operating systems interact with hardware devices directly
these add-in BIOSs are still called by modern operating systems, in order to carry out specific tasks
BIOS an algorithm FSB (Front side bus):
that carries all electronic signal information between the processor (CPU) and the random access memory (RAM)
Unit: MHz
DRAM clock (Dynamic random
access memory): Fequence of the RAM
Hardware management
Identify and initiate component hardware
Most important role to load the operating system.
The BIOS provides first instructions of the microprocessor when you turn on your computer
Hardware management Some of the other common tasks that the BIOS performs
include: A power-on self-test (POST) for all of the different
hardware components Activating other BIOS chips on different cards installed in
the computer Managing a collection of settings for the hard disks,
clock...
The BIOS is special software that interfaces the major hardware components of your computer with the operating system.
An interface To enter the CMOS Setup, you must press a certain key or
combination of keys during the initial startup sequence
A set of text screens with a number of options appears.
Common options include: System Time/Date Boot Sequence Plug and Play Mouse/Keyboard Drive Configuration Memory Security Power Management Exit
Starting diagram During the boot sequence, the BIOS is doing a remarkable amount of work to get
your computer ready to run.
When you turn on your computer, the BIOS does several things. This is its usual sequence: Check the CMOS Setup for custom settings Load the interrupt handlers and device drivers Initialize registers and power management Perform the power-on self-test (POST) Display system settings Determine which devices are bootable Initiate the bootstrap sequence
BIOS can emit one “BEEP”: end of the POST the computer will play an audible 'BEEP' If the POST completed successfully without detecting any problems with then
system will play a single short beep if a problem is detected before the BIOS initializes the video card, or a video
card is not present or not detected then the BIOS will play several 'BEEPS'
Future Extensible Firmware Interface (EFI)
EFI is intended as a significantly improved replacement of the old legacy BIOS firmware interface
A lot of advantages compared with BIOS
BIOS is written in assembly language, EFI is developed in C