Computer Start-Up

Have you ever given any thought to what happens when your computer starts up? Perhaps you have wondered what lurks behind that blue Dell screen or the E-Machine Logo. Most of us don't give it too much thought, however, some of us are naturally curious.

The computer start-up process has three basic steps:

· Power On Self Test (POST),
· Basic Input Output System (BIOS), and
· Start Up (Boot).

First let's consider what happens when we hit the power switch and how the start up files are stored. A chip (called the CMOS RAM chip) maintains a small amount of information about your floppy drive, hard disks, keyboard, CPU, etc. This chip stores these settings while the computer is on and off.

Manufacturers pretty much know that our computers suffer from a case of amnesia every time they start. As a result, they pre-program the processor to always look at the same place in the system to find their instructions.

We ensure this information is always available by placing a battery (very similar to a watch battery) in the computer. You can keep track of the effectiveness of the battery through the clock that is on the bottom right of your desktop. If you find that you are losing time or are constantly resetting your clock, your battery may be drained and in need of replacement.

When your computer is first turned on, its main system memory is empty, and it needs to find instructions to tell it what to run. It finds these instructions in the BIOS (Basic Input output System). The BIOS is built-in software that determines what a computer can do. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, and a number of miscellaneous functions.

After taking inventory of all the parts that are available, your PC will execute a Power on Self Test (POST) that verifies that basic hardware is working correctly. When POST is finished, it will normally beep, if it finds an error, it will beep multiple times and display an error message.

If everything is in order, the BIOS continues to locate communication devices (ports), input devices (such as your keyboard), and it counts RAM (memory). After this stage is successfully accomplished, control is turned over to your operating system.

Here is when we start seeing Windows load and you know the rest. Fortunately, the whole process is automatic, and for that, we are all grateful.

Now aren't you glad you asked?