О. В. Фёдорова е. В. Мезина е. В. Хамис английский язык в сфере информационных технологий и коммуникаций учебное пособие

Any computer or net virus can infect files of one or more operation systems: DOS, Windows, OS/2, Linux, MacOS and others. It is a base of this way of classification. For example virus BOZA working with Windows only is classified as Windows virus, virus BLISS – as Linux virus.

Viruses can be differed by used algorithms making them danger and hard for catching. Firstly viruses can be divided on resident and nonresident. Resident virus having come in operation memory of computer doesn’t infect memory. They are capable of copying when they are started only. We can call any macro virus resident. They present in memory during application infected by them works. Second viruses are visible and invisible. To be invisible means that users and antivirus programs can’t notice changes of infected file done by virus. Invisible virus catches all requires of operation system to read file and to record in file and shows uninfected version of file. So we can see only ‘clear’ programs during virus works. One of first invisible file infectors was FRODO and boot infector – BRAIN. Almost any virus uses methods of self-coding or polymorphism to escape antivirus programs. It means that they can change itself. Changing itself helps virus to be able work.

In conclusion a few words about future of this classification. Nowadays computer technologies and all software develop very quickly. It helps new types of computer viruses to appear. Viruses are becoming more and more dangerous and ‘cleverer’. It means that viruses can be found more and more hard. But this classification can be saved a long time thank for principles of work of computer. It means that this classification will be changed when computers work by principles that differ from principles of von Neiman. So this classification can be change by adding new subtypes of basic types if virus makers have created something new.
RADIO

RADIO transmission or reception of electromagnetic radiation in the radio frequency range. The term is commonly applied also to the equipment used, especially to the radio receiver.