VIRUS: A VIRUS
is a set of instructions (or program) or software prepared to destroy a package
and data. A virus kills data and program files. Although the purpose for
developing such soft wares is not known, they appear to be basically developed
for a check against the piracy of program packages.
Functioning of virus:
virus reside in executable files such as .COM or .EXE. Thus when PC is switched
on, the virus enters the RAM through .COM (COMMAND.COM) file and starts destructive
work of killing data and program files. Whenever the PC is switched off, they
again go back to the executable files. More than 1000 computer viruses have
been identified. They are classified as:
i)
File Allocation Table (FAT) based viruses
ii)
Key board viruses and
iii)
File based viruses
Some of the well
known viruses are:
Joshi, Die_Hard-2, Jerusalem ,
Generic, Brain, May_5th, Gumnam, World
peace etc.
VACCINE: It is software
developed for removing the viruses.
In DOS version, there are in-built programs to guard
against computer viruses. These are
Anti-virus programs for both DOS and WINDOWS and a memory
resident virus-safe program that guards against the introduction of files that
may be affected by virus.
Some of the anti-virus vaccines are:
NASHSOFT, UTSCAN, AVG, AVIRA,
Meccaf etc.