What happens when a PC boots up?
- After pressing the power button, the PC's power supply gives electricity to the motherboards and peripheral components.
- The motherboard turns on the fans.
- The motherboard's clock starts to synchronize the operation of the peripherals.
- The CPU starts the BIOS boot programm, usually at
0xFFFF0 (TODO is this correct?). Often a jump instruction. (Only if not booted up in UEFI?)
- Start POST - Power-on self test.
- Finds video card and starts its own BIOS code (usually at
0xC000).
- BIOS finds other devices and starts their BIOS (if they have one; IDE is usually at
0xC800(0)?.
- Display startup screen
- Test RAM.
- Finds hardware, plug/play, and starts them
- Display a summary screen
- Finds a MBR to start the OS boot process (for example boot process)