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

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

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

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

CMOS battery

CMOS setup utility access Press key combination during boot Delete F1 Insert Alt+S Boot with setup floppy Press Reset button twice

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

Updating your PC’s BIOS settings Activity A-1 Updating your PC’s BIOS settings

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

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

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

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

Observing the POST process Activity B-1 Observing the POST process

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

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

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

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

BIOS version

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

Updating the BIOS in your PC (Optional) Activity C-1 Updating the BIOS in your PC (Optional)

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)

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

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

Bad CMOS battery Older PCs – non-replaceable battery Newer PCs – held in socket with retaining clips

Replacing the CMOS battery Activity D-1 Replacing the CMOS battery

BIOS related symptoms Devices misidentified Wrong memory size reported during POST or available after booting Hard drive inaccessible System won’t boot from hard drive System boots from the wrong device Date and time incorrect or reset after powering off the computer

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

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

Troubleshooting BIOS and POST related problems Activity D-2 Troubleshooting BIOS and POST related problems

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