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What is a Computer
Virus?
A
computer virus is a small computer
program that makes copies of itself on
computer disks. Viruses may (directly or
indirectly) (infect) (copy to and spread
from), executable program files, or
programs in disk sectors, and even some
non-executable files which use macros.
This parasitic nature that virus programs
have is neither an accident, nor a
computer glitch. In fact, all viruses are
created by people who know how to write
computer programs.
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Why are they
called Viruses?
Experimental
self-replicating programs were first
produced in the 1960s, confirming
theories dating back to 1949. The term
virus is more recent, and was first used
in 1984 by Professor Fred Cohen to
describe self-replicating programs. The
earliest PC viruses came a bit later, in
1986-7. The name is appropriate, because
like a biological virus, a computer virus
is small, makes copies of itself, and
cannot exist without a host. (It's also a
catchier name than Parasitic
Self-Replicating Program.)
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Are all Viruses
harmful?
All
computer viruses at least take up disk
space, and many of them are able to
remain in the computer's memory, so as to
take control over some computer
functions. In addition, some viruses are
poorly written, and may cause the
computer to halt, or damage files. Many
viruses make the computer's memory
unstable, or cause programs to run
improperly. Then there are viruses
created in recent years that have been
deliberately designed to destroy data on
the disk.
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What About
Destructive Viruses?
The most
feared viruses are those that
deliberately damage or delete files, or
even destroy all data on a disk. The
vandals who produce these are concerned
only about themselves, not innocent
people who will be harmed. These vandals
hope to impress their friends, and
sometimes compete with them. Some join
groups that create new viruses every day.
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Who writes Viruses
- and why?
Viruses
can be written by anyone, anywhere in the
world, who has enough programming skill.
A few have been developed by researchers
for demonstration purposes, and some
others are jokes, written by pranksters.
Other viruses are written by people
learning programming, who think writing a
virus is accomplishing something. In many
cases, these viruses get passed around,
and later are altered by other people.
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What are Virus
symptoms?
It's
true that some viruses cause strange
things to happen. These can include:
slower operation, decreased memory, or a
disk drive LED lighting up for no
apparent reason. However, legitimate
software can also cause these effects.
And while some viruses are very obvious,
displaying messages, or even playing
musical tunes, many give no sign of their
presence. So it's important not to assume
your computer is infected, just because
strange things happen.
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How are Viruses
spread?
While
the risk is relatively small, it is
growing daily. Viruses circulate from one
computer to another, often via diskettes.
If you're lucky, you'll never encounter a
virus, but one could be concealed in the
next file you download, or on the next
diskette you receive. Diskettes borrowed
from friends, school, or work are common
sources, even shrink-wrapped diskettes
purchased at stores, or through
mail-order. Downloaded programs can be
infected, and viruses can travel among
networked PCs.
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Should you get
anti-virus software?
If
you're concerned about the virus threat,
the time to obtain anti-virus software is
before you get a virus. It's much better
to prevent a virus infection than to have
to deal with one. If your system is
virus-free, anti-virus software can help
keep it that way, providing you keep the
program updated, and check all
newly-obtained software and disks before
using them the first time.
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How can you
protect your data?
Viruses
are a threat, but data loss can also
occur from other factors. If you have
files you can't afford to lose, make sure
you have more than one copy of them. The
best way to do that is to copy hard disk
files to disk/tape, with a reliable
backup utility program. You should create
an Emergency Boot Disk, and keep it with
your backup disks/tapes in a safe place,
with write-protect tabs secured.
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How can I create
an Emergency Boot Disk?
To make
an emergency bootable floppy disk, if
using DOS, run the FORMAT A: /S command
with a disk in A> drive which is the
proper density for the drive. If using
Windows or Win95, use the option to make
a System Disk in File Manager or
Explorer, as appropriate. I'd suggest you
also COPY these commands to it, from
C:\DOS or the Win95 system directory:
ATTRIB, CHKDSK (or SCANDISK if you have
it), FDISK, FORMAT, SYS, and BACKUP and
RESTORE (or whatever backup program you
use, if it will fit). They may come in
handy if you can't access the hard
disk, or it won't boot up.
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