In this case by the end of the working day all the office will be overrun by piles of such copies, the clerks will have nothing else to do but copy the same text and give it to the neighbors - the first clerk makes two copies of the paper, the next victims of the virus make four copies, then 8, 16, 32, 64 and so on, that is the number of copies each time will increase twice.
If a desk clerk needs 30 seconds to copy one paper and 30 seconds more to pass the copies on, then in an hour there will be more than 1.000.000.000.000.000.000 copies of the virus in the office! Soon, of course, the office will be out of paper, and spreading of the virus will be stopped because of this obvious reason.
Funny as it may seem (although the participants of this incident were not at all laughing), exactly the same thing happened in 1988 in America, when several global information networks became overflow with copies of a network virus (Morris's worm), which transferred itself from one computer to another. Therefore "direct" viruses behave like this:
· "Copy this list two times and put the copies into the stacks of tasks of neighbors, if they don't already have one". The problem is solved - there is no "overpopulation", but each stack contains a copy of the virus, besides that desk clerks also manage to do their usual jobs.
"How about the destruction of data?" - an educated housewife make ask. This is very simple - it is sufficient to and to the list approximately this:
1. "Copy this list two times and put the copies into the stacks of tasks of neighbors, if they don't already have one. 2. Check with the calendar, and if the date is Friday the 13th, throw all the documents away into the waste basket."
That's about all a well-known in past the "Jerusalem" virus did (a.k.a. "Time").
By the way judging by the example with our desk clerks one may very well see why it in most cases it is impossible to say, where did the virus come from to our computer. All the clerks have the same COPIES (except for handwriting), but the original written by the hand of the bad guy is in the waste basket for a long time already!
This is the simple explanation of how a virus works. I would like to add two axioms to it, which are not obvious for everyone, strange as it may seem:
Firstly viruses do not appear by themselves - they are being created by very evil and bad hackers programers who then send them to information exchange networks or toss them to the computers of their acquaintances. Virus can not sneak to your computer by itself - either it was hiding on diskettes or even on a CD, or you have accidentally downloaded it from a computer informational network, or maybe you had virus in your computer from the very beginning, or, worst of all, some hacker lives in your home.
Secondly, computer viruses infect only a computer and nothing else, so don't be afraid - they are not being passed through keyboard or mouse.
Attempt to Give a "Normal" Definition
The first attempts to explore self multiplying artificial entities were made in the middle of this century. Von Neumann, Wiener and other authors gave definition and mathematically analyzed finite slot machines, including self multiplying ones. The term "computer virus" became known later - it is now official, that it was first used by F.Cohen (USA), a Lehigh university scholar, in 1984, on the seventh conference on computer security, which was held in the United States.