📖 IT Bible

Boot Process and POST

Boot Options

ROM (Read-Only Memory) - chip embedded in motherboard and can be upgraded through flashing

  • BIOS is program inside ROM that allows users to make changes to settings
  • if computer is losing settings or forgetting date/time, usually means CMOS battery needs to be replaced

Power-On Self-Test (POST) - diagnostic testing sequence run by BIOS to check if the hardware is working properly

  • once POST is successful, BIOS reads settings from the CMOS and searches for an OS

To configure settings inside CMOS, enter BIOS config environment

  • press valid key combo during boot up process ie. F2 or Delete

Flashing BIOS/UEFI

Flashing BIOS/UEFI - performed during upgrades, security fixes or feature improvements

  1. backup configuration and info
  2. load file into the root of the USB flash drive
  3. connect flash drive to USB port on the motherboard then reboot system
  4. BIOS/UEFI will copy firmware to system and overwrite old code

Variable beeps are used to tell if something is wrong with system

  • ie. Undetected keyboard - 2 short beeps + 1 long beep

Best practice is to disable booting from optical or USB drives to prevent system takeover by attackers

  • configure system to boot from the installed hard drive using the installed OS