Computer
viruses began appearing in the 1980s, when computers became more popular.
Viruses were originally created as jokes, and used for research and demonstration.
Soon, creators of viruses, commonly called “authors,” became more malicious
in intent. The first viruses were bits of code found attached to
popular downloadable programs, like a game or word processor. An
infected program like one of these will be downloaded and then run on a
computer. As the program is first executed, the virus is programmed
to run. The virus’s code enables it to load into the computer’s memory,
and tries to find other programs to attach it to. If it does, it
will change the program’s code so that it will include the virus’s code.
So now whenever these programs run, they can infect other programs, and
before one know it, there’s a real big mess at hand. The problem
worsens if these now infected programs are saved to a disk and shared between
many people with their own computers. Now the virus spreads from
the first computer to all of the rest of the computers.
Most
viruses have an attack phase, where the user sees some sort of effect of
the virus on the computer. Again, this effect can be benign or very
destructive. Over the years, virus authors got more sophisticated
with virus programming. A new trick they used was to infect the boot
sector of a disk. The boot sector is a piece of software executed
in the first opening stages of the loading process when the computer is
turned on. By infecting the boot sector, the virus is able to definitely
be executed and able to infect the computer while it is running; not just
while a certain program is running. Over the years, this trick slowly
died down, because people starting using floppy and hard disks less frequently,
and started using compact disks. Unlike floppy disks, CDs cannot
be rewritten or modified, and they are not traded or passed through people.
Therefore, viral infection of CDs is almost impossible.