Basic InputOutput System

1
Basic Input/Output System

• Unit objectives
• Access the BIOS setup utility and modify hardware
  configuration values
• Explain the POST and boot processes
• Install a BIOS update
• Troubleshoot BIOS and POST-related problems

2
Topic A

• Topic A BIOS and CMOS
• Topic B The POST process
• Topic C Firmware updates
• Topic D BIOS and POST troubleshooting

3
BIOS

• Software instructions on a chip (firmware)
• Enable basic computer operations
• Input/output with standard devices
• Flashing the BIOS
• BIOS shadowing

4
CMOS

• Storage area for BIOS configuration information
• Battery backed up
• Modify using setup utility

5
CMOS battery
6
CMOS setup utility access

• Press key combination during boot
• Delete
• F1
• Insert
• AltS
• Boot with setup floppy
• Press Reset button twice

7
Typical CMOS configurations

• Date and time
• CPU options
• Floppy drive options
• Hard drive options
• Serial port options
• Parallel port options
• Enable or disable integrated devices
• Enable or disable hardware support for Plug and
  Play
• Power management options
• Enable or disable hardware-based virus detection
• Boot password

8
Activity A-1
Updating your PCs BIOS settings
9
Topic B

• Topic A BIOS and CMOS
• Topic B The POST process
• Topic C Firmware updates
• Topic D BIOS and POST troubleshooting

10
POST process

• BIOS tests core hardware
• BIOS tests video subsystem
• BIOS identifies itself, including its
• Version
• Manufacturer
• Date
• BIOS tests main system memory

11
Beep codes

• 1 short beep No problems found
• 3 long beeps Keyboard error
• 8 short beeps Video adapter memory problems
• 9 short beeps BIOS problem
• 1 long 3 short beeps Memory error

12
Numeric codes

• 151 Real time clock failure
• 161 Bad CMOS battery
• 162 Configuration mismatch
• 164 Memory size mismatch
• 201 or any 20 Memory failure
• 1762 Hard drive configuration error

13
Activity B-1
Observing the POST process
14
Boot process

• You turn on the power
• Timer chip sends reset signals to CPU to prevent
  booting
• Power supply performs internal checks, sends
  Power_Good signal to CPU
• Timer stops sending reset signals to the CPU
• CPU loads the BIOS and BIOS extensions
• BIOS checks whether this is a cold or warm boot

continued
15
Boot process, continued

• If cold boot, BIOS performs the POST procedure
• BIOS reads CMOS and configures devices
• Plug and Play devices detected and configured
• BIOS determines which drive to boot from
• BIOS reads the master boot record from drive
• The OS takes over, completes the boot process

16
Topic C

• Topic A BIOS and CMOS
• Topic B The POST process
• Topic C Firmware updates
• Topic D BIOS and POST troubleshooting

17
BIOS updates

• Device problems identified as BIOS problems
• Device problems that you can attribute to no
  other cause
• Need to use new hardware options that are not
  supported by your BIOS

18
BIOS version
19
Flashing the BIOS

• Determine your current BIOS version
• Determine if a new BIOS version is available
• Download the new BIOS version installation file
• If necessary, download BIOS flashing utility from
  your PC manufacturer's web site
• Close all open applications
• Open the flashing utility and follow its
  instructions to update your BIOS.
• Restart your PC when prompted

20
Activity C-1
Updating the BIOS in your PC (Optional)
21
Minimizing BIOS upgrade risks

• Don't update your BIOS unless you must
• Never turn off your computer during a BIOS update
• Make sure to use the correct BIOS flash utility
• Follow the flash utility's instructions exactly
• Backing up your old BIOS before updating it
  (flashing utility provides this function)

22
Recovering from failed update

• Restore BIOS backup
• Boot from a floppy disk containing the correct
  BIOS and flash utility
• Set the Flash recovery jumper switch on the
  motherboard to reset BIOS to default
• Replace the BIOS chip

23
Topic D

• Topic A BIOS and CMOS
• Topic B The POST process
• Topic C Firmware updates
• Topic D BIOS and POST troubleshooting

24
Bad CMOS battery

• Older PCs non-replaceable battery
• Newer PCs held in socket with retaining clips

25
Activity D-1
Replacing the CMOS battery
26
BIOS related symptoms

• Devices misidentified
• Wrong memory size reported during POST or
  available after booting
• Hard drive inaccessible
• System wont boot from hard drive
• System boots from the wrong device
• Date and time incorrect or reset after powering
  off the computer

27
POST related symptoms

• No video, instead your computer sounds 8 short
  beeps
• The system emits three long beeps
• The system emits one long beep and then three
  short beeps
• POST code 162 is displayed
• POST code 164 is displayed

28
CMOS related symptoms

• The error message Non-system disk or disk error
  is displayed
• The error message Display Type Mismatch is
  displayed
• The error message Memory size mismatch is
  displayed
• The error message CMOS checksum failure is
  displayed

29
Activity D-2
Troubleshooting BIOS and POSTrelated problems
30
Unit summary

• Accessed the BIOS setup utility and modified
  hardware configuration values
• Explained the POST and boot processes
• Installed a BIOS update
• Resolved BIOS and POST-related problems