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

2. Computer and Information Technology for HKCEE
Introduction to BIOS
Basic Input / Output System (BIOS)
boot the computer by providing a basic set of instructions
load the operating system after turning on the computer
perform POST (Power-On Self Test)
provide set-up program for changing BIOS parameters
provide low-level routines for the communications between OS and hardware devices
DVEP

3. Computer and Information Technology for HKCEE
Introduction to BIOS
BIOS combination
BIOS program
CMOS stores BIOS program
BIOS parameter
DVEP

4. Computer and Information Technology for HKCEE
Introduction to BIOS
Advantages of storing BIOS in ROM
code and data are readily available during booting
BIOS content are not corrupted by errant applications
BIOS hardware components
BIOS ROM
PC startup program (POST)
BIOS CMOS memory
house the configuration information of individual PC
DVEP

5. Computer and Information Technology for HKCEE
Introduction to BIOS
The BIOS ROM
All BIOS are contained in ROM in old days
BIOS is now located in EEPROM chip
erased and rewritten by special programs
called flash BIOS
BIOS CMOS memory
provide a non-volatile storage for PC’s control information
need very little power to operate
powered by lithium battery
DVEP

6. Computer and Information Technology for HKCEE
BIOS chip
DVEP

7. Computer and Information Technology for HKCEE
The BIOS Boot Process
1. The power supply sends a signal to the components in the system unit.
2. The CPU finds the ROM chips that contains BIOS.
3. The BIOS performs the POST which checks components (e.g. mouse, keyboard connectors and expansion card)
The results of the POST are compared with data in the CMOS chip.
5. The BIOS looks for the system files in floppy disk drive and hard disk.
6. The system files and the kernel of the OS load into RAM from hard disk.
DVEP

8. Computer and Information Technology for HKCEE
The BIOS Boot Process
Beep codes
A series of beep: BIOS program encounter problems
One short beep: everything is normal
Errors can be indicated when video screen does not function
Interpret the beep codes by consulting main board menu
DVEP

9. Computer and Information Technology for HKCEE
The BIOS Boot Process
POST Error messages
Error messages are shown on display system
Interpret error messages by consulting owner’s manual
DVEP

10. Computer and Information Technology for HKCEE
Configuring the BIOS
Setup program interfaces
1. Hit a particular key or key combination at a right time to enter the BIOS setup utility
DVEP

11. Computer and Information Technology for HKCEE
Configuring the BIOS
Setup program interfaces
2. A BIOS setup screen is displayed.
DVEP

12. Computer and Information Technology for HKCEE
Configuring the BIOS
Typical key control
Incorrect settings of BIOS may lead to system halt
Quit the setup without saving changes if we are not sure about the changed settings
Boot sequence
control the order in which BIOS looks for an OS on start-up
usual sequence: floppy disk  hard disk  CD-ROM
DVEP

13. Computer and Information Technology for HKCEE
Configuring the BIOS
Typical key control
Performance tuning through BIOS settings
BIOS settings are responsible for how the chipset is controlled.
Chipset is the key to the overall system performance
BIOS parameters:
Choose the optimal bus speed settings
Enable the CPU’s internal cache
External cache memory
Enable system BIOS shadowing
Quick power-on self test
Update the BIOS
DVEP

14. Parts of the Boot Process
Step 1: POST
Step 2: ROM BIOS startup program searches for and loads an OS
Step 3: OS configures the system and completes its own loading
Step 4: User executes application software

15. Boot Step 1

16. Boot
Step 2

17. Boot Step 3

18. A Easy Real Life Example of the BIOS
Imagine the BIOS is the general manager of a store. The manager has to make sure all of the employees (Drivers, devices, etc) and everything is in order for opening (Booting up). So the manager (BIOS) checks all of the employees and sees if they are in working fast enough and getting the job done. If they are then the store (Computer) is in good shape. Then the general manager goes into his office and does some paper work and turns its duties to the operating system (manager). So basically when you hear BIOS, think general manager of the computer or “store.”

19. Real life Visual of how the BIOS Works
Manager
If everything’s go, Manager hands its duties to the…
General Manager
(Operating System)
(BIOS)
Checks On
General Manager
Workers
(Devices, Drivers, etc.)
Checks On
Function/Work On
Store
(Computer)

20. End…
Thank you……..