1. Introduction to Computing
Lecture-05-Starting/ Shutting Down a Computer
Muhammad Hafeez
Department of Computer Science
GC University Lahore

2. Today’s Agenda
The Process of Starting up
The Process of Shutting Down

3. Start Up/ Boot Cold Booting: Warm Booting:
Start a Computer when it is powered off
Warm Booting:
Start a computer from Operating System (Restart)
Each time system is started the KERNEL is loaded in memory
Memory Management
CPU Clock management
Allocate Resources
Start/ Stop Programs
KERNEL is memory resident

4. Steps For Booting
Step 01: Turn on, power supply send signals to components in system.
Step 02: The charge of electricity tells the processor chip to reset itself and find the ROM Chip that contains BIOS (A firmware that contains computers startup instructions)

5. Steps For Booting
Step 03: The BIOS performs a series of tests to make sure computer hardware/ Operating system is connected properly. The tests, collectively called POST (power-on self test)
Check
Buses
System
Adapter Cards
RAM
Mouse
Keyboard
Drives
LEDs flicker with POST test

6. Steps For Booting
Step 04: POST results are compared with CMOS chip. CMOS is a battery powered chip that stores data about computer configuration.
If error is found, the computer responds different for different kind of errors.

7. Steps For Booting
Step 05: If POST test is successful, BIOS searches for specific system files on available secondary storage (typical C Drive of HDD)
Step 06: After system files are loaded in RAM, the KERNEL of operating system is loaded, OS takes control of the computer.
Step 07: OS loads system configuration information in memory.

8. How the System Boot

9. Shutting Down the System
Shutting Down has three options:
Power off
Sleep Mode
Hibernate Mode
Sleep Mode: save any open program in RAM, turns off all unneeded functions, turns computer in low-powered mode.
If power is removed in sleep mode, all unsaved work is lost.

10. Shutting Down the System
Hibernate Mode: Saves open programs/ unsaved work on hard disk.

11. Questions
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