How do the computers work?
1. Back
in the 1940s, Thomas Watson, boss of the giant IBM Corporation, reputedly
forecast that the world would need no more than "about five computers."
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2. Six
decades later and the global population of computers has now risen to
something like one billion machines! -> Active
3. To
be fair to Watson, computers have changed enormously in that time. -> Active
4. In
the 1940s, they were giant scientific and military behemoths commissioned
by the government at a cost of millions of dollars apiece; today, most
computers are not even recognizable as such: they are embedded in everything
from microwave ovens to cellphones and digital radios. -> Passive
5. What
makes computers flexible enough to work in all these different
appliances? How come they are so phenomenally useful? And how exactly do they
work? Let's take a closer look! -> Active
What is a computer?
1. A
computer is an electronic machine that processes information—in other
words, an information processor: it takes in raw information (or data)
at one end, stores it until it's ready to work on it, chews and
crunches it for a bit, then spits out the results at the other end. -> Active
2. All
these processes have a name. ->
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3. Taking
in information is called input,storing information is better known
as memory (or storage), chewing information is also known as processing,
and spitting out results is called output.
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4. Each
morning, she goes to her letterbox and finds a pile of new math
problems waiting for her attention. ->
Active
5. She
piles them up on her desk until she gets around to looking at
them. -> Active
6. Each
afternoon, she takes a letter off the top of the pile, studies
the problem, works out
the solution, and scribbles the answer on the back. -> Active
7. She
puts this in an envelope addressed to the person who sent her the
original problem and sticks it in her out tray, ready to post. -> Active
8. Then
she moves to the next letter in the pile. -> Active
9. You
can see that your friend is working just like a computer. -> Active
10. Once you understand that
computers are about input, memory, processing, and output, all the junk on your
desk makes a lot more sense: ->
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11. Input: Your keyboard and mouse, for
example, are just input units—ways of getting information into your
computer that it can process. ->
Active
12. If you use a microphone and
voice recognition software, that's another form of input. -> Active
13. Memory/storage: Your computer
probably stores all your documents and files on a hard-drive: a huge
magnetic memory. -> Active
14. But smaller, computer-based devices
like digital cameras and cellphones use other kinds of storage such as
flash memory cards. ->
Active
15. It works amazingly hard and
gets incredibly hot in the process. ->
Active
16. That's why your computer has a little
fan blowing away—to stop its brain from overheating! -> Active
17. Output: Your computer probably has
an LCD screen capable of displaying high-resolution (very detailed) graphics,
and probably also stereo loudspeakers. -> Active
18. You may have an inkjet printer
on your desk too to make a more permanent form of output. -> Active
What is a computer
program?
1. As
you can read in our long article on computer history, the first
computers were gigantic calculating machines and all they ever really did was
"crunch numbers": solve lengthy, difficult, or tedious mathematical
problems. -> Active
2. Today,
computers work on a much wider variety of problems—but they are all
still, essentially, calculations. ->
Active
3. Everything
a computer does, from helping you to edit a photograph you've taken with
a digital camera to displaying a web page, involves manipulating numbers in one
way or another. -> Active
4. Suppose
you're looking at a digital photo you just taken in a paint or
photo-editing program and you decide you want a mirror image of it (in
other words, flip it from left to right). -> Active
5. You
probably know that the photo is made up of millions of individual pixels
(colored squares) arranged in a grid pattern. -> Active
6. The
computer stores each pixel as a number, so taking a digital photo is
really like an instant, orderly exercise in painting by numbers! -> Active
7. To
flip a digital photo, the computer simply reverses the sequence of
numbers so they run from right to left instead of left to right. -> Active
8. Or
suppose you want to make the photograph brighter. -> Active
9. All
you have to do is slide the little "brightness" icon. -> Active
10. The computer then works
through all the pixels, increasing the brightness value for each one by, say,
10 percent to make the entire image brighter. -> Active
11. So, once again, the problem boils
down to numbers and calculations. ->
Active
12. What makes a computer
different from a calculator is that it can work all by itself. -> Active
13. You just give it your
instructions (called a program) and off it goes, performing a long and complex
series of operations all by itself. ->
Active
14. Back in the 1970s and 1980s, if you wanted
a home computer to do almost anything at all, you had to write your own little
program to do it. ->
Active
15. For example, before you could write
a letter on a computer, you had to write a program that would read
the letters you typed on the keyboard, store them in the memory, and display
them on the screen. ->
Active
16. Writing the program usually took more time
than doing whatever it was that you had originally wanted to do
(writing the letter). ->
Active
17. Pretty soon, people started selling
programs like word processors to save you the need to write programs
yourself. -> Active
18. Today, most computer users buy,
download, or share programs like Microsoft Word and Excel. -> Active
19. Hardly anyone writes programs
any more. -> Active
20. Most people see their
computers as tools that help them do jobs, rather than complex
electronic machines they have to pre-program—and that's just as well,
because most of us have better things to do than computer programming. -> Active
What's the difference
between hardware and software?
1. The beauty of a computer is that it
can run a word-processing program one minute— and then a photo-editing
program five seconds later. ->
Active
2. In other words, although we don't
really think of it this way, the computer can be reprogrammed as many times
as you like. -> Active
3. This is why programs are also
called software. ->
Passive
4. They're "soft" in the sense
that they are not fixed: they can be changed easily. -> Passive
5. By contrast, a computer's hardware—
the bits and pieces from which it is made (and the peripherals, like the mouse
and printer, you plug into it)—is pretty much fixed when you buy it off
the shelf. -> Passive
6. The hardware is what makes
your computer powerful; the ability to run different software is what makes
it flexible. -> Active
7. That computers can do so many
different jobs is what makes them so useful—and that's why millions of us can
no longer live without them! -> Active
What is an operating system?
1. Suppose
you're back in the late 1970s, before off-the-shelf computer programs have
really been invented. ->
Passive
2. You
want to program your computer to work as a word processor so you can
bash out your first novel—which is relatively easy but will take you a few days
of work. -> Active
3. A
few weeks later, you tire of writing things and decide to
reprogram your machine so it'll play chess. -> Active
4. Later
still, you decide to program it to store your photo collection. -> Active
5. Every
one of these programs does different things, but they also do quite a
lot of similar things too. ->
Active
6. For
example, they all need to be able to read the keys pressed down on the
keyboard, store things in memory and retrieve them, and display characters (or
pictures) on the screen. ->
Active
7. If
you were writing lots of different programs, you'd find yourself writing
the same bits of programming to do these same basic operations every time. -> Active
8. That's
the basic idea behind an operating system: it's the core software in a computer
that (essentially) controls the basic chores of input, output, storage,
and processing. -> Active
9. You
can think of an operating system as the "foundations" of the
software in a computer that other programs (called applications) are built on
top of. -> Active
10. So a word processor and a chess game
are two different applications that both rely on the operating system to
carry out their basic input, output, and so on. -> Active
11. The operating system relies on
an even more fundamental piece of programming called the BIOS (Basic Input
Output System), which is the link between the operating system software and the
hardware. -> Active
12. Unlike the operating system, which is
the same from one computer to another, the BIOS does vary from machine
to machine according to the precise hardware configuration and is usually
written by the hardware manufacturer. -> Active
13. The BIOS is not, strictly speaking,
software: it's a program semi-permanently stored into one of the computer's
main chips, so it's known as firmware (it is usually designed so it can
be updated occasionally, however). ->
Passive
14. Operating systems have another
big benefit. -> Active
15. They all ran in their own,
idiosyncratic ways with fairly unique hardware (different processor chips,
memory addresses, screen sizes and all the rest). -> Active
16. That was a big problem for
programmers because it meant they had to rewrite all their programs each
time they wanted to run them on different machines. -> Active
17. Then any application will work
on any machine. -> Active
18. The operating system that
definitively made this breakthrough was, of course, Microsoft Windows,
written by Bill Gates. -> Active
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