1. Basic Input Output System
B.I.O.S.

2. 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

3. Introduction
Presentation
History

4. 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

5. 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

6. BIOS: a hardware
A component
A storage space
Evolutionarity

7. A component type of component: CMOS Supplied with a battery (lithium)
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)

8. 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

9. 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

10. 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

11. BIOS: a firmware BIOS an algorithm Hardware management An interface
Starting diagram

12. 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

13. 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

14. 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.

15. 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

16. Starting diagram BIOS can emit one “BEEP”:
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'

17. Starting diagram

18. Future

19. 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

20. Future

21. Basic Input Output System
B.I.O.S.