ss_blog_claim=1053ca87724a2435537c9f62e8524d84 ss_blog_claim=1053ca87724a2435537c9f62e8524d84

Saturday, November 15, 2008

How a Computer Starts

The usage of computer has increased rapidly and it has become part and parcel of our life. But many of us don't know how a computer starts. Let me give the entire process that is happening after we press the button of CPU. 

When we press the power button on a computer, power is provided to all the components and the boot process begins. This process happens as follows:

1. When we supply power to the motherboard on a computer, the BIOS begins a process called power-on self test(POST). During this operation, the BIOS tests important hardware that is available on the computer. 

2. BIOS first gives the control of testing process to the display adapter. That's why the first screen that appears while a computer starts is blank.

3. The display adapter then gives control back to the POST routine

4. POST tests the processor and displays the version on the screen.

5. After the processor test is complete, POST gives the control back to the BIOS. At this point, you can press the F2 key (or whatever key allows you to enter the BIOS setup on your computer) to configure BIOS settings.

6. Let us assume that we don't enter BIOS setup , BIOS tests your memory next. 

7. BIOS then checks the connections to your various hard drives, DVD drives, and floppy drives. If no connections are present, or if connections are different from what is listed in the BIOS settings, BIOS displays an error message, and the boot process halts. You must enter BIOS setup to correct these problems.

8. Assuming that all goes well, BIOS next displays a screen that summarizes the state of computer.

9. BIOS then calls a special software code named the BIOS operating system bootstrap loader 

10. After BIOS finds a bootable disk, it loads the program that is found at the Master Boot Record (MBR) of the disk into computer’s memory and gives control of the computer to that program. Assuming that BIOS gives control to the MBR on the boot partition that contains Windows XP, the startup phase now moves from the starting of your computer to the starting of Windows.

No comments: