| Computers
anyone?
What
is a computer? It is any electronic device that can receive,
handle and output information by performing calculations. The Oxford
Advanced Learner’s Dictionary defines it as follows: electronic
device for storing and analysing information fed into it, making
calculations, or controlling machinery automatically. The word
computer comes from the verb to compute, i.e. to make calculations.
There
is a tendency to believe computers are superhuman beings: this is
simply absurd. Computers are the product of man, they cannot think and
cannot solve problems or make decisions by themselves. However, they
are very effective in assisting people who are dealing with
problem-solving or decision-making activities.
Nowadays
most people are so familiar with personal computers (PC) that these have become the set image for the computer, but actually computers come in a variety of shapes and
sizes: they can be as small as a palmtop, the size of a paperback
book, or incredibly huge machines.
There
is a class of computers that is called supercomputers,
they are made of up to about a dozen CPUs and are used for
high-speed computation of large-scale scientific or engineering
problems. But they are not the biggest yet. A massively
parallel processing computer (MPP) consists of far more
CPUs than a supercomputer does. Unlike supercomputers, they are not for general-purpose computation but rather for specific tasks
that require an enormous computational capability. The first such
computer, ILLIAC IV, was designed at the University of Illinois in the
late 1960s and consisted of 64 processors, but a recent MPP computer
may consist from a few hundred to tens of thousands of processors.
Paragon XP/S of the Intel Corp., for example, consists of about 8,000
860XP microprocessors, and CM-200 of Thinking Machines Corp. is made
up of 65,536 microprocessors.
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Computer components
What
really matters in a computer is the electronic circuitry that is
located in the machine’s core. There are three
main components: the
Central Processing Unit (CPU); the memory; and the so-called buses.
The
CPU
is made up of the Control
Unit (CU), the Arithmetic
Logic Unit (ALU), and a number of Registers.
Simply put, the Control
Unit oversees the general operations and instructions that are
necessary to make the computer work. The calculations and logical
operations are performed by the ALU.
This is a very boring task, but the ALU is a fast, dumb calculator that never grumbles and is
really happy to do some elementary arithmetic, like adding or
subtracting. It is also very talented in making comparisons: it can
tell in a split second whether a number is larger or smaller or the
same as another one, or if a certain entity (for example a string of
letters of the alphabet) is equal or different from another.
Making
comparisons is a vital function for a calculator, and a lot of things
can be done this way: for example you can determine whether you still
have money in your bank account, or if an aeroplane is allowed to take
off in a congested airport, and also if the book you have finally
decided to borrow from your local library is still available.
Registers
are helpful devices that act as “containers” of data or
instructions, their task is to help speed up the processing of the
data. There are various kinds of registers: some just keep the data
and make them available when needed, some keep track of where the data
are memorised (their “address”, literally speaking), while others
hold the result of a specific computation. Registers are controlled by
the CPU.
As
with human beings, intelligence cannot be confined to logical skills,
it has to interact with mnemonic faculties: for computers it is very
much the same. The data have to be memorised in order to be processed.
Remembering which data are being used, where they are and how they are
to be manipulated during the processing, is essential. To handle the
enormous amounts of data we need storing devices. There are mainly
two: the Random Access Memory (RAM) and the Read-Only Memory (ROM)
One
should think of a computer system as an intricate set of highways that
has to secure optimal communication among its various components.
This job is mostly performed by buses, which move data along I/O
(Input/Output) paths between the processor and the other components.
The invention of the local bus in 1992 made the “contact” with the
processor closer, causing a dramatic increase of processing speed.
Nowadays Intel
Corp. has developed bus designs that support Plug and Play
systems, yet another way to boost computer performance, whose main advantage is
that the system automatically recognises a peripheral the moment it
has been connected to the computer, so that all the configuration
procedure can be avoided.
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What computers actually do
Computers
handle data and perform seven basic types of operations:
INPUT:
When you feed data into the computer by means of a keyboard, mouse or
any other peripheral input device.
OUTPUT:
When the computer hands out some kind of information as a result of
data processing, like when you see something on the screen or print a
text or graphic.
STORAGE:
When you memorise data in some parts of the computer. For example the
hard disk, a floppy disk or a CD-ROM.
RETRIEVAL:
Is the opposite operation, i.e. when the computer reads back data
previously stored.
SENDING:
When data are sent from one computer to another by means of network
facilities.
RECEIVING:
the opposite of SENDING.
PROCESSING:
Is the work performed on the data through calculations, combination,
rearrangement, and so on.
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