Introduction to Computing Lecture-05-Starting/ Shutting Down a Computer Muhammad Hafeez Department of Computer Science GC University Lahore
Today’s Agenda The Process of Starting up The Process of Shutting Down
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
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)
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
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.
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.
How the System Boot
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.
Shutting Down the System Hibernate Mode: Saves open programs/ unsaved work on hard disk.
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