The power switch is flipped.

A burst of electricity suddenly comes lurching into your PC's brain. Human experience: Alarm clock buzzing in ear.

The I'm all here check takes place.

The computer does a quick check of its vitals. It checks for the keyboard, microprocessor, monitor, and a few other things not worth mentioning. The disk drives also wind up as part of this step. Your hard drive may click once; the floppy disk(s) will make the "uhn-uhn" sound. Comparable Human Experience: Get out of bed, make sure arms, legs and head are still attached regardless of the dream you were having.

If anything is missing, the computer either beeps or displays a cryptic message. The purpose of this stage is to make sure that the computer has all its parts. If anything is missing, an error message is displayed or the computer beeps, explaining the problem in Morse code.

So far everything has happened before DOS was loaded. It's just your computer trying to find its arms and legs.

The startup message appears.

The computer is OK so far, so the manufacturer displays the startup and copyright information on-screen. Human Experience: Seeing self in mirror, hearing spouse call name, etc.

This message just provides distraction because watching a blank screen at this stage tends to make PC users nervous. The startup message you see is different for each computer make and model.

The computer does a quick inventory of all its memory, and other vital components may perform self-tests. On some models, you may actually see the memory totals tally up. Some video systems display various tests on the monitor. Human Experience: Weigh self on scale; inspect face for signs of same self seen last night in same mirror; grumble.

The computer is now making doubly sure everything works properly. This step is a good idea. After all if any thing is wrong it is better to know now rather then be disappointed later.

Memory tests are often slow. Especially if you have a lot of memory. On some PCs, you can skip the memory tests by pressing the spacebar.

The last thing your PC does before it loads DOS is beep once. This beep means everything is OK, and it's actually a happy beep because DOS hasn't been placed into memory and controlling your PC's mind.

Your computer begins to look for a control program on one of the computer's disk drives. It looks first to the A floppy drive (which is why you'll hear it crunch after the beep), and then it looks on your 'C' hard drive. Human Experience: Looking for a pair of pants that fit.

The computer is dumb by itself and can't do anything (other than its self-test described earlier). It needs a control program. Just like your car needs a human to set the speed and direction and obey most of the traffic laws, your PC needs DOS, or some other operating system, in the driver's seat.

The computer first looks to load an operating system from drive A, primarily with respect to tradition. Before the days of hard drives, PCs just came with one or two floppy drives, A or B. When the hard drive (labeled C) was added, the computer's BIOS (Basic Input Output System) was updated to also look there for an operating system. Still the order is drive A first, then drive C (the hard drive).

You see the Starting MS DOS message on screen. The secret DOS files form the core of DOS. These are the system files. The important thing to remember here is that these two files are DOS's guts and vital to your PC's operation. Human experience: you listen to a subliminal message tape, one that instructs you on how to be a nicer person, on the way to work.

The command processor is a fancy name for the command.com program. This program produces the DOS prompt and is responsible for running your programs and carrying out DOS's most essential commands. Human experience: finally at work, you start obeying the unwritten laws of human nature and play nice with the other kids.

You don't really talk to DOS when you use a PC. Instead, you talk with a program that takes your instructions and converts them into the basic grunts and squawks that the computer can understand.

In summary, the command processor is a program that provides a user interface between you and DOS, it interprets your commands for DOS itself and translates your whims into orders.

A bunch of DOS commands or programs are run automatically when DOS starts. You see the results of this on your screen. Lots of copyright messages and other related stuff appear, and maybe some programs automatically pop up in your face. Human Experience: you have a to-do list and you actually have the time and motivation to do everything on that list.

This happens when the operating system runs a file called Config.sys. This contains instructions that tell DOS about your computer. There are two types of instructions; those that tell DOS how much memory it can use for working with disk drives and other items and those instructions that tell DOS how to control any strange devices that may have attached themselves to your PC. You'll see some stuff displayed on the screen: some startup messages and other information that looks potentially serious but goes by too fast to be threatening. Human Experience: mother dresses you.