Computer viruses

Elena Safronova

Baltic Russian Institute

1 year, BA.

Riga, 2004

Plan:

1. What is a computer?

2. Base configuration of the computer system

2.1 System unit

2.2 Monitor

2.3 Keyboard

2.4 Mouse

3. Internal devices of the system unit

3.1 Motherboard

3.2 Hard drive

3.3 Floppy dick drive and CD-ROM

3.4 Video card

3.5 Sound card

4. Systems of the mother board

4.1 RAM (Random Access Memory)

4.2 Processor

4.3 Chip of ROM and system of BIOS

4.4 Volatile memory

5. Peripheral devices of the PC

5.1 Data input devices

5.2 Data output devices

5.3 Data exchange devices

6. Functions of operation system of a computer

7. Software

1. What is a computer?

The computer is an electronic instrument, intended for automation, creation, storage, processing and transportation of the data.

Computer - the universal information computer. One of main assignments of a computer is processing and storage of the information. With appearance of the computer began possible to operate inconceivable earlier with information contents. In the electronic form translate the libraries containing scientific and artistic literatures. Old photos and film-archives find a new life numerically.

2. Base configuration of the computer system

The personal computer is universal technical system. His configuration (structure of the equipment) can be changed as required. But there is a base configuration which contains 4 devices : system unit, monitor, keyboard and mouse.

2.1 System unit

In a system unit are placed the most important components which are called internal. To a system unit also are connected external and peripheral units. On appearance system units differ with the form of tank. Tanks can be horizontal (desktop) and vertical (tower).

2.2 Monitor

Monitor is the device of a visual data representation. This is main output device. Key parameters of the screen monitor: size, frequency of upgrade (regeneration) maps, a class of protection.

2.3 Keyboard

The keyboard is the key control unit of the PC. Is used for input of the alphanumeric (sign) data, and also commands of handle.

2.4 Mouse

The mouse is the control unit manipulation type. As against the keyboard the mouse cannot be used on a straight line for input of the sign information - the principle of handle is event. Movements of the mouse and clicks of buttons are events.

3. Internal devices of the system unit

3.1 Motherboard

The motherboard is the host board of the PC. It contains: the processor, a microprocessor package (chipset), buses, the RAM, ROM (permanently storage device) and plugs for connection of additional devices.

3.2 Hard drive

Hard disk is the main device for long-time storage of the big sizes of the data and programs.

3.3 Floppy disk drive and CD-ROM

For operative carry of small information amount use floppy disks which are inserted into a special disk drive. Standard floppy disk has a size of 3.5 inches, which capacity is 1.4 Mb. It is labeled by characters HD (high destiny).

The principle of operation of the device will consist in reading numerical data with the help of the laser ray mirrored from a surface of a disk. The digital recording on CD differs from record on a diskette with high density.

3.4 Video card

Together with the monitor the video card will derivate a video system of the PC. During existence of the PC some standards of video cards were replaced: MDA (Monochrome); CGA (4 colours); EGA (16 colours); VGA (256 colours); SVGA (16.7 mln colours). Key parameters of a video card: screen resolution, colour permission (colour depth) and video expedition (plane and three-dimensional).

3.5 Sound card

The sound card processes sounds, music and speech. The sound is reproduced through the external stereo speakers connected to a sound card. Key parameter of a sound card is the word length determining quantity of bits per second.

4. Systems of the mother board

4.1 RAM (Random Access Memory)

RAM is a file of the crystal cells, capable to store the data. There is a dynamic (DRAM) and static (SRAM) memory.

Chips of a dynamic memory use as the main RAM of a computer. Chips of static memory use as an auxiliary memory (cache memory) intended for optimization of operation of the processor.

4.2 Processor

The processor - a main chip of the PC in which all calculations are made. The processor consists of cells in which the data can vary. Internal cells of the processor are named as registers.

Key parameters of the processor: an operating voltage, a digit capacity, working clock rate, coefficient of an internal clock multiplying, a size of the cache memory.

The processor is connected to other devices of a computer groups of the explorers called as buses. Main 3 buses: the address bus, the data bus, the bus of commands.

The address bus is connected to it the processor for copying data from a cell in one of registers.

The data bus. On this bus there is a copying data from the RAM in registers of the processor and back.

The bus of commands - commands act from the RAM, from areas where programs are stored.

4.3 Chip of ROM and system of BIOS

The chip of ROM (permanently storage device) is capable to store long time the information, even when the computer is switched off.

BIOS (Basic Input Output System) – main assignment is to check up structure and working capacity of the computer system and provides interaction with keyboard, monitor and hard disk.

4.4 volatile memory

The data are stored in a chip about floppy and hard disks, about the processor and some other devices of the motherboard. Due to this chip the computer precisely watches time and a calendar.

5. Peripheral devices of the PC

Peripheral devices of the PC are connected to his interfaces and intended for execution of auxiliary operations. Due to them the computer system gains flexibility and scalability.

5.1 Data input devices

Devices of input of the sign data - the keyboard

Device of command handle - the mouse and special manipulators: the trackball (installed permanently, the ball is actuated by a palm), (pen mouse clone of a ball pen), the infra-red mouse (wireless link with a system unit.).

Devices of input of graphic data is scanners (are intended for input of the graphics information on paper), data tablets (are intended for input artistic graphic information) and digital cameras.

5.2 Data output devices

As the output device of the data, in addition to the screen monitor, use printing stations - printers, permitting to receive copies of documents on a paper or transparent carriers.

By a principle of operation distinguish: matrix, laser, LED and ink-jet printers.

5.3 Data exchange devices

Modem - the device intended for information interchange between remote computers. Key parameters of the modem: productivity (bits/s), supported communications protocols and error corrections, the bus interface (ISA or PCI).

6. Functions of operation system of a computer

Operation system represents the complex of system and auxiliary resources. OS is a support for program supports of higher level - applied and majority of the auxiliary applications.

Basic function of all operation systems is intermediary. It consists in support of several sorts of interface:

user interface (between the user and soft-hardware of a computer)

hardware-software interface (between program and hardware)

program interface (between different sorts software).

7. Software

Programs for work with the text.

Text editor is the elementary program for input of the text.

Word-processor - allows not only to enter and edit the text, but also to make it out.

Spreadsheets.

Spreadsheets are used for work with figures. It is possible to enter numbers, formulas and explaining text into cells of spreadsheets. Spreadsheets are capable to transform numbers in graphs and diagrams.

Control systems of databases.

Databases name the huge data files, organized in tabulated structures. The basic functions of control systems by databases are: