Software is the set of programs designed to solve problems on your PC. Software configuration - the composition of the PC software.
The software can be divided into three categories:
1. The system software (public program), performing various support functions, such as making copies of the information used, the issue of reference information about your computer, check the computer device health, etc.
2. The application software, ensures the implementation of the necessary work on the PC: editing text documents, create drawings or pictures, the processing of information files, etc.
3. The tool software (programming system) ensuring the development of new programs for the computer programming language.
§ This public program is not associated with a particular use of a PC and performs the traditional functions: planning and task management, input-output control, etc.
§ In other words, system programs perform various support functions, such as making copies of the information used, the issue of reference information about your computer; check the computer device health, etc.
By the system software includes:
§ operating system (this program is loaded into memory at startup);
§ program - shell (provide a more convenient and intuitive way to communicate with a computer than with a DOS prompt, for example, Norton Commander);
§ Operating envelope - front-end systems, which are used to create graphical interfaces, multiprogramming it;
§ Drivers (software for managing ports of peripheral devices, usually loaded into memory when the computer starts);
§ Utility (or auxiliary utilities that represent the user a number of additional services).
It should be noted that some of the utilities included in the operating system and the other part is functioning autonomously. Most of the general (system) software is part of the OS. Part of the overall software is a part of the computer (a part of OS control programs and tests recorded in ROM or PROM installed on the system board). Some common software refers to a stand-alone program and is available separately.
Applications can be used singly or in a package or software systems.
Application software - programs that directly support the implementation of the necessary work on the PC: editing text documents create drawings or pictures, creating spreadsheets, etc.
Application software packages is a system of programs for the use of the field is divided into problem - oriented, general purpose packages and integrated packages. Modern integrated packages contain up to five functional components: Test and spreadsheet, database management, editing, telecommunication facilities.
Tool software or programming system - a system to automate the development of new programs in a programming language.
In the most general case of creating a program for the selected programming language (the system programming language) must have the following components:
1. A text editor to create a file with the source code of the program.
2. The compiler or interpreter. The source code using compiler program translates into an intermediate object code. The source code of a large program consists of several modules (source files). Each module is compiled into a separate file with the object code, which then have to be combined into one unit.
3. The linker or assembler who performs binding object modules, and outputs a functional application - executable code. Executable code - is a complete program that can be run on any computer where the operating system for which the program was created. As a rule, the resulting file has an extension of .EXE or .COM.
4. In recent years, a proliferation of visual programming techniques (using scripting languages), focused on the creation of Windows-based applications. This process is automated in an environment of rapid design. It uses ready-made visual components that are configured by using special editors.
All modern operating systems provide for the creation of the file system, which is designed to store data on the disks and access to them.
The main function of the file system can be divided into two groups:
1. Options for the files (create, delete, rename files, etc.).
2. Functions for working with data stored in files (write, read, search data, etc.).
It is known that the files are used to organize and store data on storage media. File - a sequence of an arbitrary number of bytes, which has its own unique name or a named area on storage media.
Structuring a plurality of files on storage media by means of directories that store attributes (parameters and properties) files. Directory may include multiple subdirectories, resulting disk file branched structures are formed. The organization of files in a tree structure called a file system.
The principle of file system organization is table. Information about where in the recorded file on the disk is stored in the file allocation table (File Allocation Table, FAT).
This table is located at the beginning of the volume. In order to protect the volumes it stores two copies of the FAT. In case of damage to the first copy of FAT disk utilities can take advantage of the second copy to restore the volume.
To file structure maintenance functions include operations taking place under the operating system:
- creation of files and assign a name;
- creation of directories (folders) and assign a name;
- rename files and directories (folders);
- copying and moving files between the computer and disks between directories (folders) of the disc;;
- delete files and directories (folders);
- navigate the file structure for access to a specific file, a directory (folder);
- management of file attributes.
1.3.3. Classification of operating systems
The operating system is the basis of PC software. The operating system is a complex system and office software, which provides user-computer interaction and performance of all other programs.
On the one hand, it is based on a basic PC software, included in his system BIOS, on the other hand, she is a support for the software of higher levels - applications and most service applications.
In order for the computer to work, it must be set (written) operating system on the hard drive. When the computer is turned on, it is read from the disk space and is located in the RAM. This process is called the operating system loads.
Operating systems differ in features of the implementation of computer management algorithms, usage areas.
Thus, depending on the control algorithm, processor, operating system, divided into:
1. The single-tasking and multi-tasking.
2. Single-player and multiplayer.
3. Uniprocessor and multiprocessor systems.
4. Local and network.
By the number of tasks running simultaneously operating systems are divided into two classes:
1. The single-task (MS DOS).
2. Multitasking (OS / 2, Unix, Windows).
The tasking system used peripherals controls, file management tool, a means of communicating with users. Multitasking operating systems used by all agents that are characteristic of single-task and, moreover, control the shared resource sharing CPU, RAM, files and external devices.
Depending on the areas of application multi-tasking operating systems are divided into three types:
1. Batch Processing Systems (ES OS).
2. The time-sharing system (Unix, Linux, Windows).
3. Real-Time Systems (RT11).
Batch processing systems are designed to solve problems that require rapid results. The main purpose OS batch is the maximum bandwidth or the maximum number of tasks solution per unit time.
These systems provide high performance when processing large amounts of information, but reduce user productivity online.
In systems with time sharing for each task is allocated a small amount of time, and none of the problem does not occupy the CPU for a long time. If this time interval is chosen minimal, it creates the appearance of multi-tasking. These systems have lower bandwidth but provide a high performance user interactively.
Real-time systems are used for process control or technical object, for example, flying objects, machines, etc.
According to the number of concurrent users on the OS computers are divided into single-user (MS DOS) and multiplayer (Unix, Linux, Windows 95 - XP)
In multi-user operating system, each user configures a user interface, i.e., You can create your own sets of shortcuts, programs, groups, set individual color scheme, move to a convenient location taskbar and add the new Start menu items.
In multi-user operating system, there are means of protection of information of each user from unauthorized access by other users.
Multi-processor and single-processor operating systems. One of the important features of the operating system is the presence of means of support for multiprocessor data processing. Such facilities exist in OS / 2, Net Ware, Widows NT. By way of the organization of the computational process, these operating systems can be divided into symmetrical and asymmetrical.
One of the most important features of a computer classification is to divide them to local and network. Local OS used on stand-alone PC or a PC that are used in computer networks as a client.
The structure of the local operating system includes client-side software to access remote resources and services. Network operating system designed for PC management included in the network to share resources. They represent a powerful means of access to information, its integrity and other features use of network resources.
1.3.4. MS DOS operating system
One of the most common operating systems until the mid 90-ies was a disk operating system from Microsoft MS DOS (Microsoft Disk Operating System).
In modern Windows OS to work with DOS commands using the command line, which can cause: Start / Run, in the dialog box, type command and click OK. Another way to call the command line: - Start / Programs / Accessories / Command Prompt.
The composition of the MS DOS
The main modules are included in the operating system MS DOS:
Output (BIOS) - 1. A basic input.
2. Boot Record (Boot Record).
3. BIOS Expansion Module (IO.SIS).
4. The interrupt processing unit (MS DOS.SYS).
5. The command processor (COMMAND.COM).
6 files, drivers who, after loading them into memory provides work devices such as a mouse, CD-ROM and others.
7. Utilities OS operating various service functions (formatting disks, etc.).
Basic system BIOS hardware dependent and is in memory ROM PC. This part of the operating system is built into a PC.