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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
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Basic Input Output System B.I.O.S.
Plan of the presentation • Introduction • Presentation • History • BIOS: a hardware • A component • A storagespace • Evolutionarity • BIOS: a firmware • BIOS an algorithm • Hardware management • An interface • Startingdiagram • Future
Introduction • Presentation • History
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 • Intermediarybetween 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
BIOS: a hardware • A component • A storagespace • Evolutionarity
A component • type of component: CMOS • Particularity: lowenergyconsumption • Directly implant on a motherboard or a periphericcard • ROM (90s) • Manufactured by the designer of Mother-Board • Can’tbealtered • PROM / EPROM / EEPROM (90 to Nowadays) • A first version wasimplement in • Manufacture release update • Can be update • Suppliedwith a battery (lithium) • Save personnal change (except Rom)
A storagespace • BIOS is a storage space: • stored in a permanent way • lithium battery • lowenergyconsumption • a memory of reduced size • No more than 100 bytes • contains: • parameters • functions
Evolutionarity • computer system cancontainseveral BIOS firmware chips • plug-in adapter cardssuch as SCSI, RAID, Network interface cards, and videoboardsincludetheirown BIOS • Add-in cardsusuallyonlyrequiresuch an add-in BIOS if they: • Need to beusedprior to the time that the operating system loads • Are not sufficiently simple, or generic in operation to behandled by the main BIOS directly
Evolutionarity • Older operating systemssuch as DOS may continue to ake use of the BIOS to handle input and output • most modern operating systemsinteractwith hardware devicesdirectly • theseadd-in BIOSs are stillcalled by modern operating systems, in order to carry out specifictasks
BIOS: a firmware • BIOS an algorithm • Hardware management • An interface • Startingdiagram
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 • DRAMclock (Dynamicrandomaccessmemory): • Fequence of the RAM
Hardware management • Identifyandinitiate component hardware • Most important role to load the operating system. • The BIOS provides first instructions of the microprocessorwhenyouturn on your computer
Hardware management • Some of the othercommontasksthat the BIOS performsinclude: • A power-on self-test (POST) for all of the different hardware components • Activatingother BIOS chips on differentcardsinstalled in the computer • Managing a collection of settings for the hard disks, clock... • The BIOS isspecial 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 keysduring the initial startup sequence • A set of textscreenswith 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
Startingdiagram • During the boot sequence, the BIOS isdoing a remarkableamount of work to getyour computer ready to run. • Whenyouturn on your computer, the BIOS doesseveralthings. This isitsusualsequence: • Check the CMOS Setup for custom settings • Load the interrupthandlers and device drivers • Initializeregisters and power management • Perform the power-on self-test (POST) • Display system settings • Determinewhichdevices are bootable • Initiate the bootstrapsequence • 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 isintended as a significantlyimproved replacement of the oldlegacy BIOS firmware interface • A lot of advantagescomparedwith BIOS • BIOS iswritten in assemblylanguage, EFI isdeveloped in C
Basic Input Output System B.I.O.S.