HISTORY OF COMPUTERS.
Blaise Pascal, the French philosopher and mathematician, was
only nineteen when he invented a calculating machine in 1642.
It was a mechanical device based on a series of ten-toothed gear
wheels. Pascal's machine was improved by the German
mathematician Gottfried W. Leibniz, whose machine could also
multiply and divide.
The progress in technology brought in by the Industrial
Revolution convinced Charles Xavier Thomas de Colmar, a
French business-man, to start the production of a new type of
machine in 1820. From 1820 to 1890 thousands of Colmar's
machines were sold: it was an incredible success.
However, it was Charles Babbage's Analytical Engine which laid
the basis of today’s computers in 1822. The Analytical Engine
combined toothed gear and punched cards and could make
calculations only providing it with the necessary figures.
MS - DOS
At the end of the nineteenth century electricity was used to
power new models of calculators, which became faster and
faster and spread all over the world. An American Statistics
expert, Herman Hollerith, devised an electrical calculator which
used a new type of punched card. He founded a company, the
International Business Machines, and travelled for years to
promote his calculators: in 1923 there were 100 of them in Great
Britain and 216 in Germany.
In 1943 the University of Pennsylvania proposed a new type of
calculator optimized to aim guns to the U.S. Army. It was a true
electronic computer and was built in 1946 by three engineers at
the University of Pennsylvania, J. Presper Eckert, John W.
Mauchly and Herman H. Goldstine, using 18,000 vacuum tubes.
The ENIAC (so it was called) weighed 30 tons and was 180
square metres large!
In 1945 an Hungarian engineer at the University of Princeton,
John von Neumann, designed a computer which could keep
instructions inside an electronic memory and use them to process
data. Von Neumann's idea was applied to many models in U.S.A.
and Europe. Large companies, like IBM, produced thousands of
computers, but they were still very difficult to be used because
they needed long series of instructions based on complicated
programming languages.
Two facts contributed to the diffusion of computers: the development of BASIC, an easier programming
language, in an American college in 1965 and of DOS by Bill Gates. Gates was a student who had an idea:
converting programming into instructions written in English. He called his set of instructions Disk
Operating System and started producing it for IBM computers. Then he founded a company, Microsoft,
and furter developed his idea, converting instructions into images. The new user interface was called
Windows and its versions are used today in almost all computers in the world because they facilitate
interaction with PCs.
WHAT IS A COMPUTER?
A computer is an electronic device used to process
information. It accepts a set of instructions (program)
and a set of characters (data) and supplies results
after processing data with the program installed.
A computer has different types of memories: a ReadOnly Memory (ROM), a Random Access Memory
(RAM) and also a Hard Disk (HD). The ROM is
permanently installed inside a chip and contains the
start-up information; it is operated automatically
when a computer is switched on. The RAM is used to
store programs temporarily; it requires a continuous
power supply and is cancelled when a computer is
switched off. The HD is a magnetic disk inside the
computer cabinet where programs and data can be
stored. It is part of the computer’s hardware,so
access to programs is considerably faster. It contains the operating system (normally Windows).
By hardware we generally mean the physical units which make
up a computer: monitor, keyboard, central processing unit, etc.
The CPU is built into a single microprocessor chip: usually
Pentium or AMD. Attached to the CPU there are many different
types of peripherals, some installed inside the cabinet (disk
drives, sound cards, graphic cards, etc.), others linked with
cables (printers, scanners, etc.).
Output devices, like monitor and printer, show the operator the
results of the operations performed. Input devices are required
to transfer programs and data inside the computer. The
keyboard is one of them, but disk drives and disks or CDs containing software can also be used.
By software we mean programs executed by computers. The basic software inside a computer must
include an operating system, which tells the CPU how to operate the hardware and to run the software.
The most famous was MS-DOS (Microsoft Disk Operating System) created by Bill Gates. Today it is
included in Windows, the newer GUI (Graphical User Interface).
HOW A COMPUTER VIRUS WORKS
Viruses are programs whose basic aim is to damage a computer. As biological viruses, they infect files
and self-replicate in order to infect other files and computers. However, computer viruses cannot directly
damage hardware, only software is damaged directly.
Normally their target is the operating system, but they can infect different types of files: the most
common are executable files, but they may be hosted by word processors or spreadsheets in the form of
macro scripts.
As there are many types of viruses, the correct term is malicious software, or malware, which includes not
only viruses, but also trojan horses and worms. A trojan horse is a piece of software which is attached by
its creator to a useful program and may allow him to take control of the infected computer or to host and
activate another virus. A worm is similar to a virus, but does not need a host file: it modifies the operating
system to spread itself. Today’s malware also includes programs which collect and send information
about users to private businesses without notifying. They are called spyware or adware and their spread
has been facilitated by the diffusion of the Internet, e-mails and file sharing systems.
Viruses and other malware can be stopped updating regularly antivirus software and using firewalls.