Chapter 5Basic Input/Output System (BIOS)
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Transcript of Chapter 5Basic Input/Output System (BIOS)
Chapter 5Chapter 5 Basic Input/Output Basic Input/Output System (BIOS)System (BIOS)
5.1Introduction to BIOS 5.2The BIOS Boot Process 5.3Configuring the BIOS
5.15.1 Introduction to BIOSIntroduction to BIOSBasic 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
5.15.1 Introduction to BIOSIntroduction to BIOSBIOS combination
BIOS program
CMOS stores BIOS program
BIOS parameter
5.15.1 Introduction to BIOSIntroduction to BIOSAdvantages of storing BIOS in ROM
code and data are readily available during booting
BIOS content are not corrupted by errant applications
BIOS hardware componentsBIOS ROM
PC startup program (POST)
BIOS CMOS memoryhouse the configuration information of individual PC
5.15.1 Introduction to BIOSIntroduction to BIOSThe BIOS ROM
All BIOS are contained in ROM in old days
BIOS is now located in EEPROM chiperased and rewritten by special programs
called flash BIOS
BIOS CMOS memoryprovide a non-volatile storage for PC’s control information
need very little power to operate
powered by lithium battery
5.15.1 Introduction to BIOSIntroduction to BIOSBIOS chip
5.25.2 The BIOS Boot ProcessThe BIOS Boot Process1. 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)
4. The results of the POST are compared with data in the CMOS chip.
5.25.2 The BIOS Boot ProcessThe BIOS Boot Process5. 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.
5.25.2 The BIOS Boot ProcessThe BIOS Boot ProcessBeep 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
5.25.2 The BIOS Boot ProcessThe BIOS Boot ProcessPOST Error messages
Error messages are shown on display system
Interpret error messages by consulting owner’s manual
5.35.3 Configuring the BIOSConfiguring the BIOSSetup program interfaces
1. Hit a particular key or key combination at a right time to enter the BIOS setup utility
5.35.3 Configuring the BIOSConfiguring the BIOSSetup program interfaces
2. A BIOS setup screen is displayed.
5.35.3 Configuring the BIOSConfiguring the BIOSTypical 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 sequencecontrol the order in which BIOS looks for an OS on start-up
usual sequence: floppy disk hard disk CD-ROM
5.35.3 Configuring the BIOSConfiguring the BIOSTypical key control
Performance tuning through BIOS settingsBIOS 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
ENDEND