basics about BIOS.

1. Prepared By: Prasad Kumar
Swain
Stream : MCA 2nd
SEM
Regd. No : 0505247102
Guided By : Manas Kumar Nayak

3. An introduction to the BIOSAn introduction to the BIOS
One of the most common uses ofOne of the most common uses of
flash memory is for the basicflash memory is for the basic
input/output system of yourinput/output system of your
computer commonly known ascomputer commonly known as
BIOS.BIOS.
The importance of the BIOS is that itThe importance of the BIOS is that it
performs all of the function the pcperforms all of the function the pc
needs to get startedneeds to get started

4. What BIOS DoesWhat BIOS Does ..
The first thing the BIOS does is check theThe first thing the BIOS does is check the
information stored in a tiny (64information stored in a tiny (64 bytesbytes) amount) amount
of RAM located on aof RAM located on a complementary metalcomplementary metal
oxide semiconductoroxide semiconductor (CMOS) chip. The(CMOS) chip. The
CMOS Setup provides detailed informationCMOS Setup provides detailed information
particular to your system and can be alteredparticular to your system and can be altered
as your system changes. The BIOS uses thisas your system changes. The BIOS uses this
information to modify or supplement itsinformation to modify or supplement its
default programming as needed. We will talkdefault programming as needed. We will talk
more about these settings later.more about these settings later.

5. Interrupt handlersInterrupt handlers are small pieces of softwareare small pieces of software
that act as translators between the hardwarethat act as translators between the hardware
components and the operating system. Forcomponents and the operating system. For
example, when you press a key on yourexample, when you press a key on your
keyboard, the signal is sent to the keyboardkeyboard, the signal is sent to the keyboard
interrupt handler, which tells the CPU what it isinterrupt handler, which tells the CPU what it is
and passes it on to the operating system. Theand passes it on to the operating system. The
device driversdevice drivers are other pieces of software thatare other pieces of software that
identify the base hardware components such asidentify the base hardware components such as
keyboard, mouse, hard drive and floppy drive.keyboard, mouse, hard drive and floppy drive.
Since the BIOS is constantly intercepting signalsSince the BIOS is constantly intercepting signals
to and from the hardware, it is usually copied, orto and from the hardware, it is usually copied, or
shadowedshadowed, into, into RAMRAM to run faster.to run faster.
Contd…

6. BIOS usual sequenceBIOS usual sequence
• Check the CMOS setup for customCheck the CMOS setup for custom
setting .setting .
• Load the interrupt handlers & deviceLoad the interrupt handlers & device
driver.driver.
• Perform the power-on-self test(POST).Perform the power-on-self test(POST).
• Initialize register & powerInitialize register & power
management.management.
• Display system setting.Display system setting.
• Determine which device are bootable.Determine which device are bootable.
• Initiate the boot strap sequence.Initiate the boot strap sequence.

7. The steps in the system Boot processThe steps in the system Boot process
Power Initialization
BIOS Startup
POST
Video & Device BIOS
System Check
Plug and Play Check
Summary Display
Boot Device found
Operating system Running

8. System Boot SequenceSystem Boot Sequence
• When you turn on the pc’s power switch, the internal
power supply initializes itself.
• As soon as the power supply is able to supply reliable
power to the motherboard, it transmits a “good power”
signal to the motherboard chipset.
• Then motherboard chipset sends a “system reset”
command to the processor.
• Due to this command the CPU reads the first instruction
from jump address.
• Jump address is fixed in system memory having
address “FFFFoh” which contains the physical address of
BIOS boot program on the ROM BIOS Chip.
•CPU executes the first instruction which copies the BIOS
program into system memory & starts BIOS running.

9. POST (Power on self test)POST (Power on self test)
• At the time of system start up ROM BIOS is
only chip get active first. It is sending one-one
signal or electric pulse to the devices those who
are connected to the motherboard. If it is getting
the return signal from those devices then it will
display the summary on the display screen and
this is known as POST .
•If BIOS founds the system is ok it will go to
search the booting devices like :- HDD, CDD or
FDD.
•If it founds any booting files then it boots
system or starts the operating system.

10. The BIOS checks to see if this is a cold
boot or a warm boot. It does this by
checking the value at memory address
0000:0472. A value of 1234h indicates
a warm boot, and the BIOS skips the
rest of POST. Anything else is
considered a cold boot.
Cold & Warm BootCold & Warm Boot

11. THE SETUP UTILITYTHE SETUP UTILITY
Menu Bar : On the top of the screen the menu bar: On the top of the screen the menu bar
is present with the following selections.is present with the following selections.
Main : Use this main to make changes the: Use this main to make changes the
basic system configuration.basic system configuration.
Advanced : Use this menu to enable and make: Use this menu to enable and make
changes to the advance features.changes to the advance features.
Power : Use this menu to configure the power: Use this menu to configure the power
management or enable the power managementmanagement or enable the power management
features.features.
Boot : Use this menu to configure a default: Use this menu to configure a default
system devices used to locate and load the operatingsystem devices used to locate and load the operating
system.system.
Exit : Use this menu to exit the current: Use this menu to exit the current menumenu
or toor to exit the setup programs.exit the setup programs.

13. Navigation KeyNavigation Key Function of the KeyFunction of the Key
F1 Displays the general help menu
Escape (Esc)
Jumps the exact menu or return to
the main menu from the submenu.
← →
Select the menu item to the left or
right.
↑ ↓
Moves the highlighted bar up or
down between the fields.
Enter
Brings the selected menu for the
highlighted field.
Home/ Page Up Move the cursor to the first field.
End/ Page down Move the cursor to the last field.
F5
Reset the current screen to the
setup default.
F10 Save changes and exit the setup.

14. For P-III PcsFor P-III Pcs

15. Standard CMOS setup: This setup page includes all the
items in standard compactable BIOS.
Advance BIOS setup: This setup includes all the items for
the BIOS special enhanced feature.
Chipset Feature setup: This setup page includes all the
items for chipset special feature. As the name suggests this
section we can change and modify critical parameter of chipset on
that motherboard.
Power Management setup: This setup page includes all
the items for power management setup.
PnP/ PCI configuration: This categories specifies the
value of the timer for the PCI component and set the IRQ values
for the PCI devices.
Load BIOS default: In this section we can set default values
for the system.
Load performance default: In this section we can save
the standard performance of the system.

16. Integrated peripherals: In this setup page we can set
the items for integrated peripherals.
User password: In this section we can set a password for a
user of the computer.
Supervisor password: In this section we can save a
password for the supervisor of the computer.
HDD auto detection: In this menu of BIOS setup BIOS will
automatically configure the HDD parameter present in the
computer.
Save and exit setup: Save all the CMOS values changes to
the CMOS and exit the BIOS setup.
Exit without saving: Cancel all the CMOS values changes
and exit the BIOS setup.

17. BEEP CODESBEEP CODES
• Not all beep codes means something bad.
• Nearly all BIOS programs will sound a
single beep code to indicate that all is well
and then continue the boot process. But often
we catch the beep codes as surprisingly
sounded first.
• Each BIOS produces has its own post error
beep codes.
As an example:- IBM standard, AMI, Award
& phoenix are having their own standard
beep codes.

18. Bios Suppliers Keyboard Commands
ALR (Advances Logic Research.inc) ® PC / PCI F2
ALR PC non / PCI CTRL+ALT+ESC
AMD® (Advanced Micro Devices.Inc) BIOS F1
AMI (American Megatrends. Inc) BIOS DEL
Award BIOS CTRL+ALT+ESC
Award BIOS DEL
DTK (Datatech Enterprises Co.) BIOS ESC
Phoenix BIOS CTRL+ALT+ESC
Phoenix BIOS CTRL+ALT+S
Phoenix BIOS CTRL+ALT+INS

19. Beep codes for fault finding:Beep codes for fault finding:
BEEPBEEP MEANINGMEANING
No BeepNo Beep Power supplies failurePower supplies failure
Repeating short BeepsRepeating short Beeps Power supply or systemPower supply or system
board failureboard failure
One short BeepOne short Beep POST is completePOST is complete
Two short BeepTwo short Beep POST ErrorPOST Error
One long One short BeepOne long One short Beep Mother board FailureMother board Failure
One long two short BeepOne long two short Beep VDA FailureVDA Failure
Three long BeepThree long Beep Key Board errorKey Board error
One long three short BeepOne long three short Beep VDA errorVDA error

20. AMI BIOS Fault Finding:AMI BIOS Fault Finding:
BEEPBEEP MEANINGMEANING
One short BeepOne short Beep POST is completePOST is complete
Two short BeepTwo short Beep RAM FailureRAM Failure
Three short BeepThree short Beep Memory Parity FailureMemory Parity Failure
Four short BeepFour short Beep System Time FailureSystem Time Failure
Five short BeepFive short Beep Mother board FailureMother board Failure
Six short BeepSix short Beep Key Board failureKey Board failure
Seven short BeepSeven short Beep CPU failureCPU failure
Eight short BeepEight short Beep VDA failureVDA failure
Nine short BeepNine short Beep ROM BIOS check error.ROM BIOS check error.