Theme 2. Software. Windows Ms-office. Information networks

1. Software

The program is an ordered set of instructions (instructions, directives) and instructions executed by the computer.

Executing program commands in a given sequence leads to a specific data change on the computer.

The software can be divided into three groups:

• system: operating systems, service programs, drivers, etc. - provide PC operation, distribution of its resources, support dialogue with the user;
• Applied: text and image editors, databases, spreadsheets, etc. - provide solutions to various tasks of human activity;
• instrumental: programming languages.

To create software products, hundreds of people-years of skilled work (for example, the Windows system) are spent.

There is copyright in software products and should be respected.

2. Operating Systems

Operating systems (OS) are software complexes that are downloaded automatically when you turn on your computer and provide the work of existing PCs, exchange data between them, organize user dialogue, detect false and non-standard situations, PC diagnostics, and more. 

The operating system is an integral part of the computer. The most common systems are MS-DOS, Microsoft, OS / 2 , IBM, UNIX, AT & T, WINDOWS 95, LINUX, etc. As part of the OS, you can select parts: command language, file system, and drivers.

Command language - a set of commands that are entered by the user from the keyboard to perform the specified actions, such as launching the program, issuing the catalog, etc.

Drivers - special programs for controlling external devices. Drivers expand the capabilities of the OS management of external devices (keyboard, mouse, printer, CD-ROM, scanner, etc.

Operating system shells

Operational shells - programs that give the user more visibility and convenient tools for working with a PC. They implement graphical or text interface, the exchange of information between applications, devices, and the user.

One of the most common was the NC shell (Norton Commander) for the MS-DOS operating system. The NC has two panels, each of which can depict the contents of the directory on the disk, the directory tree on the disk, information about the files and directory, and so on. At the bottom of the panel are shown function keys, at the top - the menu commands.

Windows Graphic Layout

Windows is a high-performance, multi-tasking 32/64-bit graphical user interface operating system. 

Windows do not require MS-DOS and have powerful and convenient configuration and configuration tools.

In 1985, the first version of the Windows shell appeared, and in 1990 - Windows 3.0, which was a great success. In August 1995, Windows-95, in 1998, Windows-98, then Windows 2000, Windows XP, Windows 7, ... Windows 10.

The benefits of Windows are achieved by significantly increasing the load on the hardware of the computer. A significant drawback of Windows is that it has fairly low reliability.

Scalable fonts do not contain bitmap (pixel) characters of some fixed size, but the outlines of symbols that allow you to build symbols of any desired size.

The image of characters on the screen and when printing is formed from one and the same contours in the font file - they are fully consistent with one another (the principle of WYSIWYG - what you see is what you get, which is on the screen, that and is printed).

Windows understands fonts other than TrueType, including PostScript Type fonts (Adobe Systems), which are widely used in publishing and printing.

Means of data exchange. To organize data exchange, Windows offers:

• clipboard: a memory location for exchanging data in a program or between programs in which the cut or copied object temporarily moves (text, images, files, etc.);
• Dynamic Data Exchange (DDE) - the ability to use data created by other programs (for example, a text editor can use a table created by a table processor);
• Object Linking and Embedding (OLE) mechanism is an improvement of DDE tools. An application that employs "embedded" data can edit this data, which automatically triggers the program by which this data was created.

Desktop (Desktop). After loading the system, we find ourselves on the desktop, which contains various graphics objects, working tools, folders (in the name of the folder can contain up to 255 characters), shortcuts (shortcut icons), and a taskbar ( taskbar ). Standard (system) folders (shortcuts) - My Computer, Network Neighborhood, Recycle Bin, etc.

Windows Add-ons

The Paint Image Editor allows you to create and edit drawings and save them in graphics files of WMD and PCB formats. The editor has a minimal set of image processing tools.

The WordPad Text Editor is a set of tools for preparing and printing documents.

Calculator - allows you to make non-complex calculations.

Windows provides work with networks, email, multimedia.

File system

File system - a set of files and directories on external devices, as well as programs that work with them. The most commonly used file organization is FAT 32 (File Allocation Table).

As a physical file carrier, flexible, hard disk drives and optical drives are used.

Disk C: usually splits into several areas (logical drives), which may have the names D:, E:, etc. For the optical disk, the first letter after the name of the logical disk is used.

A file (from the English file - a dossier, a set of documents) is a program or an organized set of data having its name and placed in memory as a whole.

Each file has a name and its type (extension). The file name can contain up to 8 characters (except for Windows), and extensions - up to three characters. By extension, you can define its character (tab.).

Tabl. File extensions

Each file is registered in the contents of the files - the directory (directories, folders), similar to the contents of the book.

Explorer is a powerful tool for working with the file system: organizing files and folders, renaming files and folders, creating a new folder, moving and copying files and folders, and more. Explorer allows you to access documents, folders, and programs using the computer resources tree and also illustrates the organizational hierarchy of Windows.

New devices turn on virtually without user intervention (Plug & Play).

3. Service software (utilities)

To implement - programs of auxiliary (service) appointment. The service software includes archivers, antivirus, packers, russifiers, diagnostic programs, optimizations, access restrictions, etc.

Archiver. Archival copies are used to create archives that allow you to pre-compress information from 20 to 90%. 

Among the most well-known and widely used archivists include PKZIP, PKUNZIP, ARJ, RAR, PKPAK, PKUNPAK, LHA.

Antivirus programs. Computer virus - a small program that joins the file or the middle of the program and can independently multiply (create their copies). The action of the virus manifests itself in different ways from the wrong program operation to spoil all the data on the disk.

To detect and eliminate viruses, many anti-virus programs have been developed, including AVP, Aidstest, Doctor Web, NOD32, and others. For example, "Kaspersky Lab" (1997) is engaged in antiviral research since 1989.

4. Applied software systems

There are tens of thousands of applications of a different nature.

Systems of preparation of texts

Text processors allow you to prepare documents on a PC. An example of word processors is Word, PageMaker, Lexicon, and many others.

Table Processors

Electronic tables (processors) - software systems that are designed to work with tables of numbers, presentation of results in the form of charts, diagrams, etc. 

Electronic tables allow you to store in a tabular form not only a large amount of initial data, the results of calculations but also communications (mathematical relationships) between them, whose values are automatically recalculated according to the formulas when changing the values of the initial data.

An example of spreadsheets is Excel, Quattro Pro, SuperCalc, Lotus, etc. 

Documents created in the Excel environment are called books. Each book consists of sheets of the following types of sheets: work, diagrams, macros, modules in the language Visual Basic.

Database Management Systems (DBMS)

Databases - the only, centralized data warehouse of a certain domain. 

Each program has access to specific database data using special programs called database management systems. DBMS software products are FoxBASE, FoxPro, Access, etc.

Types of data organization and communication between them:

• Hierarchical (in the form of a tree) - there is the ordering of elements in the record, one element is considered the main one, others - subordinates.
• Network - there is an opportunity to install horizontal links in addition to vertical hierarchical connections.
• Relational (from the English relation - relationship) - in the form of rectangular tables.

The main objects of the database are:

• Tables are the basis of the database. In the database information is stored in a separate two-dimensional table. When working with data from multiple tables, links are established between tables.
• Queries - are created to search and select data from a table that satisfies certain conditions.

Powerpoint

PowerPoint is designed to prepare various kinds of presentations. In these presentations, you can use audio and video streams.

Computer graphics systems

There are two types of graphics: raster and vector.

Raster graphics - An image consists of points (pixels) that store information about brightness and color. 

Applied in artistic practice. An example of raster graphics systems is Paint, Photoshop, CorelDraw, and others.

Vector graphics - the image is constructed using a mathematical description of simple objects - line, circle, etc. 

Applied in engineering practice. An example of vector graphics systems is AutoCAD, Illustrator, and many others.

Computer Mathematics Systems

Systems of computer mathematics are intended for the decision of mathematical problems: Mathcad, Maple, Mathematica, Matlab, Derive and others.

5. Information networks

Networks

Information processes - search, collection, storage, transmission, processing of information.

Computer network - a group of several computers, interconnected with the help of cables (radio channels) for the transmission of information.

Computer networks allow providing: collective processing of data by users connected to the network; sharing programs; sharing devices.

Networks are local, regional, global. Any network is built on the basis of several powerful computers - servers. To connect computers to the network, you need the appropriate network equipment and software.

Internet (Inter - a general Net - network) - a worldwide computer network, which unites tens of thousands of heterogeneous local and global computer networks into a single whole. The Internet is a grid of networks - the ability to transfer information between any computer around the world, regardless of their platforms.

The international network was created in the '60s within the framework of the military program and then turned into a global network of public use, which contains a huge amount of information resources.

Protocols are needed to organize the work of the PC in the grids. To date, the Transmission Control Protocol / Internet Protocol (TCP / IP) has been developed. World Wide Web (Simplified Web, WWW) works on the basis of this standard.

To work with the Internet you need an appropriate program, which is called a browser (browser - from the English to browse the book, scroll). 

With the Netscape Navigator and Microsoft Internet Explorer browsers, we have access to all of its resources to the Internet.

In addition to the communication line and the modem, you must have a provider - an organization that provides you access to the Internet. To get to the Internet you must first get to the node of the network (server).

Data transmission channels

Data transmission is realized through various channels: telephone cable; radio communication; electrical wires. 

The most reliable channel is a special communication channel (dedicated line).

Modem - converts a digital signal from the PC into an analog signal to transmit it along the line. The modem should be high-speed.

Connecting to the Internet through a cable TV network provides a higher data transfer rate of up to 10 Mbps.

A digital subscriber line (DSL) provides speeds up to 115 Kbc.

Domestic networks - a local network of the house (or several neighboring ones) via RadioEthernet indirect visibility or in another way creates a transmission channel. 

Advantages of a home network at a data rate (about 100 Mbps) that can be used for conferences, gaming battles, etc.

Internet services

Email - E-mail allows you to organize a single mail system within a diverse corporate network.

FTP and TFTP are tools for accessing file archives for file sharing between local and remote computers.

Teleconferencing - an e-mail message is sent to one address and automatically distributed to all conference participants (subscribers).

WWW is based on hypertext technology: it has a friendly interface; makes a transition on servers; searches for information on the hypertext web; allows you to easily work with graphics data in virtually all formats.

Web - document (Web - page) is an electronic document written in HTLM (* .htm) format and contains hypertext links.

The search server is a dedicated network of the Internet that searches, collects, and organizes information that is available on all other network servers, for example, HTTP: // yahoo.com.

6. Questions for self-examination

1. What is commonly understood as the term 'software'?
2. What is the level of software sharing?
3. A set of programs of that level form the core of the operating system?
4. What functions does the kernel of the operating system do?
5. What are the basic level programs?
6. What classes of programs do you know at the service level?
7. With the help of programs of a class, you can enter, edit and design text data?
8. What do you know about categories of graphic editors?
9. In which cases is it appropriate to use automated translation systems?
10. What is an interpreter and a compiler? What is the difference between them?
11. What is a computer virus?
12. How does the virus infect your computer?
13. How do computer viruses work?
14. What do you know about sources of computer virus infection?
15. What signs can you detect the fact of infection with a computer virus?
16. What types of viruses do you know? What destructive actions do they carry out?
17. What measures are recommended to prevent infection by a computer virus?
18. What is an antivirus? What types of antivirus do you know?
19. What is a heuristic analyzer? What features does it perform?
20. Give examples of antivirus programs. Briefly describe them.