1. CS101
Booting A Computer

2. Booting Up A Computer Dilemma
To get our computer running we need the OS
To survive when the computer is turned off the OS must be saved to a storage device, usually the hard drive
The OS knows how to get software off of the hard drive so it can run on the computer, but the OS is in the hard drive when the computer tries to start so it cannot get itself out of the hard drive
How does the computer start up without the OS?

3. Simplified Booting of a Computer
When you press the Power button…
… an electrical signal is sent to the to your systems Firmware.
The firmware has the special ability to be able to store zeros and ones without any power being supplied.
The Firmware will perform a Power On Self Test (POST) to make sure the basic hardware is working.
The firmware points to the UEFI hidden partition on the computers hard drive.
The UEFI partition will find the partition that has the Operating System stored.
The Operating System starts loading it into RAM and the processor.

4. Unified Extensible Firmware Interface
UEFI
Contains most of the directions to get your computer started.
It will find the partition that has the operating system and start it running.
Invented by Intel in mid ’s.
Used by Macs and newer Windows computers.
It makes booting a computer more secure and has more options then the old BIOS’s it is replacing.

5. Why do we care how a computer starts?
Because you can do a lot of things if you
know how to alter the startup of a computer!

6. You can … Change startup settings. Make your computer more secure.
Test a computer’s hardware.
Restore a computer to an earlier time.
Reinstall your Operating System.
Repair your disk drive.
Lot’s more.

7. Mac Recovery Mode https://support.apple.com/en-us/HT201314
You can also hold down keys at startup to effect settings.
Startup key combinations for Mac

8. Windows 10 Advanced Startup Options