Booting or rebooting your computer won't stub your toe


A friend with a new computer called in a panic (I get a lot of panic calls). His machine was hopelessly frozen and he didn't know what to do.

"Why don't you boot it?" I asked.

There was a small, gurgling sound at the other end of the line. I took this to mean that Jack didn't understand the instructions.

"You know, just boot the computer again," I repeated.

Jack was not amused. "I just paid two grand for this thing. You may kick your computer around, but I'm not touching this one."

Another piece of technobabble misunderstood. I should have known better. While booting or re-booting a computer is something that all of us have to do from time to time, it's a term that novices find a bit foreign -- and if they're like Jack, a bit disconcerting.

Booting a computer is another term for turning it on, while re-booting technically refers to restarting the machine internally without flicking the power switch. In practice, the two are used interchangeably.

The phrase is a strained metaphor that deals with what happens inside your computer when you turn on the power.

Computers typically check first to make sure their internal hardware is OK. IBM-compatibles include a memory test, which accounts for the numbers clicking off on your screen.

Once that's done, a small built-in program tells the computer to check the first floppy disk drive. If there's a disk in the drive, the computer tries to read the first sector of the disk.

If the floppy disk contains the operating system -- the underlying software the computer needs to communicate with its internal parts and with you -- the computer will find on that first sector a small part of that operating system called a bootstrap loader.

If there's no disk in the floppy drive, the computer will grunt, look at the hard disk and try to do the same thing -- find the bootstrap program.

This program tells the machine how to load the rest of the operating system and present itself to you as a useful tool. In essence, the computer pulls itself up by its own bootstraps.

For this reason, the first sector of a disk is called the boot sector and turning a machine on is known as booting the system.

(And, because all computers go through the same type of boot process, malicious hackers frequently choose the boot sector as the entry point for viruses that may trash your system later. That's one good reason never to boot from a floppy disk whose pedigree is unknown.)

You'll know the computer is booting properly because the disk drive light will blink rapidly as the operating system loads.

On IBM-compatibles, you may get nothing at the end but a prompt telling you what disk drive the machine booted from, or a series of incomprehensible messages if the machine automatically loads other programs in the process. Apple Macintosh computers are friendlier. You'll get a smiley face and a "Welcome to Macintosh" message while the operating system loads, and the familiar Mac desktop will appear at the end.

You may wonder why the computer always looks at the floppy disk first, even when it has a hard disk drive. It's a safety precaution. If the computer tried the hard disk first and the boot sector or operating system were corrupted, the machine could freeze with no way out. The only alternative would be replacing the hard disk.

By checking the floppy drive first, the computer always gives you a chance to start up a usable disk and a clean version of the operating system. That's why it's always a good idea to have a couple of floppy disks with your operating system on hand.

In any case, from time to time you'll have to re-boot your computer. This usually occurs when faulty software ties up your system to the point at which it no longer responds to the keyboard. IBM-compatibles don't provide any inherent warning of this calamity. The machine just freezes or the screen goes haywire.

The Mac operating system is more sophisticated. It usually figures out when some horrible mistake has occurred and displays a little picture of a bomb (yeah, those Mac programmers are real cute) with a message that says, "System Error."

Re-booting your computer essentially tells it to go back to square one -- the point at which it starts looking for the boot sector on the floppy drive. It will erase everything in memory, and load the operating system again. The only good thing about re-booting is that it saves the wear an tear of turning your computer off and on.

If you have a Macintosh, you can frequently reboot by choosing the "Restart" function from a pull-down menu at the top of the screen.

IBM-compatibles take the strong-arm approach. To re-boot, you have to hold down the CONTROL, ALT and DELETE keys simultaneously. The programmers chose this awkward combination because it requires both hands -- it's virtually impossible to do accidentally.

Sometimes a program will hang the computer up so badly that it won't respond to the CTRL-ALT-DEL combination. Newer machines usually have a reset button on the front to force the hardware to reboot. With older machines, you may have to turn the power off, wait a few seconds and turn it on again.

So that's the story on booting your computer. Of course, if it crashes and trashes the last two chapters of your dissertation or last month's payroll figures, you may be tempted to boot it for real -- as in out the window. Take a deep breath and try CTRL-ALT-DEL instead.

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