1. Computer Startup

2. Power
Electricity Warms up components
And heads to the CPU

3. BIOS Basic Input / Output System chip with it’s programs called.
BIOS runs POST

4. CMOS
The CMOS Chip contains the most fundamental information, like basic computer components setup and the date
That is why it needs a battery
CMOS: Complementary Metal Oxide Semiconductor

5. POST
Power On Self Test
You may hear some drives or other actions as your computer is being tested
More than one beeps indicates a problem with the tested hardware
In some BIOS two beeps is OK

6. POST
Power On Self Test

7. POST
BIOS compares memory records with the CPU to ensure they are running right

8. Bios Actions Load Device Drivers Load Interrupt Handlers For: Keyboard
Mouse
Hard Drive
Floppy Drive
Etc.

9. The System Timer is Checked
To ensure proper pacing
Above – the worlds most flexible clock

10. Check System Bus
BIOS has CPU Check System Bus to ensure all components are functioning.
From Webopedia.com:
system bus
The bus that connects the CPU to main memory on the motherboard. I/O buses, which connect the CPU with the systems other components, branch off of the system bus.
The system bus is also called the frontside bus, memory bus, local bus, or host bus.

12. POST tests memory and video

13. Option to run BIOS
F2 or DEL

14. Why? Some settings may need to be set
Hard Drives
You may need to change the boot order
Hard Drive CD
Write down key settings before changing them!

15. Cold Boot or Warm Boot
The computer had stored a value in memory to indicate if the computer was simply restarted with a “warm boot”.
Warm boot – BIOS is done.
Cold boot – Continuing…

17. RAM Test
All Ram Written and Read

18. (above are just some useful images of disks and connections)
All Drives Tested
(above are just some useful images of disks and connections)

20. Operating System Started
This process is the Boot.
BIOS Transfers control to the OS
Can have multiple Operating Systems – Including more than one
Windows
Linux
Etc
OS is on the Hard Drive

21. Windows Starts
Hardware Gets Recognized by Windows

22. Further Initialization
Plug and Play
Drivers for PCI (and ISA)
Disk Drives fully initialized
Video Drivers Loaded
Services Added, such as disk defrag and partition

23. Logon

24. There you go!