When diagnosing and repairing computer problems, every computer goes through a series of systematic steps before the operating system comes up on the screen. If you suspect a computer to be a dead machine it may not be. Some troubleshooting and basic diagnoses can uncover the problem. What the end user see's on a screen when Windows or another Operating system puts it logo on the monitor is the end result of allot of steps, mostly hardware. To diagnose hardware problems you must understand how the hardware works.
When power is applied by pressing the ON button, power is applied to the mother board. Once applied the computer BIOS (Basic Input output system) goes through a series of steps. It looks for the keyboard first and then the video controller or video card. Users can recognize this by the video card information flashing quickly across the monitor. The computer inventory is checked which is stored in the CMOS memory such a floppy drive, cdrom and hard drive. Once all inventoried hardware is checked and passes, control is passed to the hard drive controller and looks for what is called the boot sector of the hard drive and the operating system is loaded into ram which results with the logo which we've all see on the screen. Again if any check fails, the computer does will stop at the point of failure, which sometimes is not easily identifiable.
It's actually kind of interesting what the computer actually does for it looks like a machine that thinks like a human, but the computer is a machine which can only process information sequentially one step at a time and can only process information which it is fed. Diagnosing and repairing a computer really isn't that hard. Look at it this way. In the morning when you wake up, there is a certain process which you go through to get ready for the day. The process doesn't change, we don't even think about it, but it's mostly the same routine from day to day what we do. The computer is no different. Every time it gets turned on, it goes through the same steps also.