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This article introduces the relevant knowledge of "the basic concept of DOS". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

DOS is the most basic operating system software, and DOS is the abbreviation of English Disk Operation System. The DOS operating system used in microcomputer is mainly MS-DOS developed by American Microsoft company and PC-DOS developed by IBM company. Since its birth in 1981, DOS operating system software has experienced a process of continuous improvement and improvement, and its version has gradually developed from 1.0 to 5.0,6.0,6.22, which has been widely used so far. The MS-DOS6.22 version introduced here includes many novel and powerful commands.

The function of DOS system

In order to coordinate the work of various parts of a computer system and give full play to its efficiency, a manager is needed to reasonably dispatch its various resources-hardware and software resources. DOS operating system is such a manager.

Resources in computer systems are usually divided into four categories: processors (CPU), memory, external devices and information. DOS operating system has the management function of these four resources.

The CPU model used in the early PC series of microcomputers is 8088 (8086). In the past decade, 80286, 80386, 80486 and 80586 (also known as PENTIUM, or "Pentium") have become more and more powerful. DOS 6.22 supports all of the above CPU.

For computers using 8088 or 8086CPU, limited by the conditions at that time, the ability to access memory is limited to 1MB. The capacity of RAM in memory is generally 640KB. The early versions of DOS are designed for the above hardware.

Although the memory range that advanced CPU can manage has reached 16MB (80286) and 4096MB (80386, 80486), the version of DOS has also been upgraded to 5.0,6.0,6.2. However, in order to maintain compatibility with earlier versions of DOS, DOS still limits the memory space that users can use directly to 640KB, which is also known as basic memory.

Startup of DOS system

1. The composition of DOS system

DOS system is made up of a set of important programs provided by floppy disk or hard disk. The core of DOS system consists of three startup modules and a boot program (Boot). The three startup modules are input and output module (IO.SYS), file module (MSDOS.SYS) and command processing module (COMMAND.COM). The role of the bootstrap program is to load the two implicit DOS startup modules IO.SYS and MSDOS.SYS into memory when the computer starts. The main role of IO.SYS is to manage input / output devices. The role of MS-DOS.SYS is to manage disk files and system resources. COMMAND.COM is the outermost module of the whole DOS system, and its task is to interpret and execute the commands entered by the user.

2. Startup of DOS system

To use the DOS system on disk, the DOS system must be called into the internal memory of the computer, which is called the startup of the DOS system.

In addition to the need to start DOS when booting (this kind of start-up is generally called cold start), if the microcomputer is running in a "dead cycle" or other "dead cycle" for some reason, it also needs to restart DOS (this start-up is generally called hot start). Press the (Ctrl) + (Alt) + (Del) key to restart DOS. Some microcomputer panels are equipped with a button (Reset), which can also be used to restart DOS.

The boot of DOS can be divided into two types: boot from floppy disk (A drive) and boot from hard disk (also known as C disk). For microcomputers with hard disk, the priority of these two ways can be set by modifying CMOS. If the priority is set to "DOS C:", then look for the DOS system in drive An at startup, boot from disk A, and look for DOS system from hard disk C if not; conversely, if the priority is set to "Claxine A:", look for the DOS system in hard disk C at startup, and if not from floppy disk A.

There are also two important files in the DOS file, which are in the root directory of the same boot disk:

(1) config.sys is the system configuration file. Users can use it to define the arrangement of memory in advance, and so on, so that the hardware of the system can play a better role.

(2) autoexec.bat is a batch file that executes automatically at startup as specified by the system. It can

Automatically executes a series of DOS commands (internal and external commands) before the user performs keyboard operation, which can set system environment variables, search path, system prompt, screen or printer mode, and start user programs.

(3) the mainframe of all kinds of microcomputers with 80286, 80386 and 80486 as CPU is equipped with high-energy battery, the clock can continue to run after shutting down, and the date and time can be read out automatically when the computer is turned on.

Start DOS with floppy disk

(there is no autoexec.bat file on this disk).

Insert the boot disk into drive An and close the door.

After power on, the following information is displayed on the screen:

Current date is Wed ll-24-1993

Enter new date (mm-dd-yy):

If there is an error between the display date and the current date, you can enter the correct value (in the format: month-day-year) and press the enter key to correct it, otherwise press the enter key directly. After asking for the date, the following information is displayed on the screen:

Current time is 11:52:50.38a

Enter new time:

The operation of asking for time can be handled in the same way as the date operation.

The sign that the startup ends normally is that the DOS prompt A:\ > appears on the screen, which means that the microcomputer is currently under the control of the DOS system, waiting for the user to enter a command. The letter "A" means that "current disk" is disk A. When the microcomputer is equipped with more than one disk drive, such as A disk, B disk, C disk, the command to set a disk as the current disk is:

D: (enter) (d: is the drive letter)

If you want to change the current disk from disk A to disk C, you should click the following underlined part:

A:\ > C: (enter)

The screen shows:

C:\ >

[example 2.1.2] start DOS with hard disk C.

A the drive door should not be closed.

After power on, the screen generally displays the following content:

C:\ >

Text

Under the DOS operating system, the information on disk is stored and managed in the form of files. In computer science, a file is a collection of related information, which can be programs, data, sounds, games, or other information, generally recorded on a storage medium (such as a disk). Each file has its own name, called the file name. When you need to use a file, as long as you indicate the corresponding file name, the DOS system can accurately find the file and perform operations such as reading and writing.

1. Naming of files

In order to distinguish different files so that they can be executed, modified, and found, the DOS operating system specifies that the file name consists of a file master name and an extension. The format is as follows:

□. □□□

It can be composed of 1-8 characters before the decimal point, which is called the principal name. It can be composed of 0-3 characters after the decimal point, which is called the extension.

For example: G9401.DBF, where G9401 is the principal name and DBF is the extension. The characters that can be used for file primary names and extensions are:

(1) English letter: Amurz (case equivalent)

(2) numerals: 0-9

(3) Chinese characters

(4) Special symbols: $# & @ ()-[] ^ ~, etc.

Space characters, various control characters, and the following characters cannot be used in file names:

. "/ <) Ten:;, *?

Because these characters have been used for it.

Because some names have special meaning in DOS, we cannot use them as file names, such as:

CON- console (screen or keyboard)

COM1- > Asynchronous Communication Transmission Port (Serial Port)

The naming of files, in addition to generally following the conventions of the DOS system, can be decided by the user. In order to facilitate management and memory, it is recommended to use the main name and extension with certain meaning in English or Hanyu pinyin.

If you can use Letter01.txt to represent the letter with serial number 01, use GZ9601.DBF to represent the salary database of a unit in January 1996.

2. Polysemous file name and file name wildcard

A file name is generally used to specify a file. In practical use, it is sometimes necessary to process a batch of files at the same time. For example, to copy several files at a time, or to list a group of related file names, we can use the wildcard "?" And "*" to deal with it, so that you can easily achieve your goal.

(1) character "?" Indicates that it can be any character at that position

(2) the character "*": indicates that it can be any string starting from its position.

A document shown in a polysemous file name table.

* .DOC test1.doc test2.doc

Titled. * test1.doc test2.doc temp1.dot temp2.d te1.6a

? ringing. * program1.prg program2.prg graph.img gra.img

PRO*.* program1.prg program2.prg

Thanks to gl.dbf g.bas gra.img.

GR? . * gra.mg

TE?? 1. * te8t1.doc temp1.dot

TEST? . * t68t1.doc t68t2.doc

*.? Te1.ba letter

3. Extension of the file

The file extension under DOS system has some special meaning, and some can be automatically generated by some specific software.

Special extension:

Extension special definition COM executable file EXE executable file BAT batch file SYS system configuration file

Extensions generated by specific software:

A software BAK backup file with a specific extension, such as an old file retained by the word processor, a program file generated by the BASBASIC language, a database file generated by the DBFdBASE (or FoxBASE) system, a program file generated by the PRGdBASE (or FoxBASE) system, a document file generated by the DOCWORD word processing software, a program file generated by the CC language.

File directory

1. Tree directory

A directory is established when a disk is initialized, which is called the root directory of the disk, and we can put the files in the root directory in turn.

With the development of disk technology, the capacity of disk is getting larger and larger, so it is no longer difficult to hold hundreds of files on one disk. However, putting a large number of files in the root directory can cause problems in two ways:

First, the root directory established by the DOS system can hold a limited number of files, the root directory of the 360KB disk holds up to 112 files, while the 1.2MB and 1.44MB disks hold up to 224 files; second, it is disorganized to concentrate a large number of files in a directory, which makes it inconvenient for users and DOS systems to operate.

This is just like the library's management of books: if the books purchased are numbered in the order in which they are purchased, it will bring a lot of inconvenience to search and other work, so the library divides books into major categories such as Chinese, mathematics, foreign languages, and so on. Chinese category can be subdivided into primary and secondary schools and other small categories for management, its shape is like an upside down tree.

Similarly, the DOS system adopts a tree directory structure, that is, the DOS system not only allows files to be stored in a directory, but also allows it to set up its subordinate directory, called a subdirectory, in a directory; if necessary, the user can establish a subdirectory of the subdirectory. In this way, on a disk, its directory structure may be composed of a root directory and several subdirectories and subdirectories. What it's made up of.

With the tree directory structure, we often concentrate the files of the same application system in a subdirectory, or the same type of files in a subdirectory, or set up different subdirectories for different users. Everyone uses their own subdirectories and does not interfere with each other.

2. File identifier

With the tree directory structure, to specify a file on a disk, not only the file name should be given, but also the path of the file-search path should be given. When you ask the computer to do something, you have to tell the computer where to get it and where to put it, just like writing the address of the recipient and writer on the envelope instead of just the name. A path in DOS is a set of directory names that arrive at a specified file from the root directory (or the current directory). If the first symbol in the path is a backslash ("\"), it represents the root directory. Directory names are also separated by a backslash ("\").

Several drives are often installed on a microcomputer, so in order to specify a file during file operation, DOS must give the following three elements: disk letter, path and file name, which constitute the file identifier of a file. The general form of a file identifier is:

"Drive letter"path] (file name)

Paths and file names are also generally separated by a backslash ("\").

According to the concept of file identifiers, it is not difficult to understand:

(1) DOS does not allow two files with the same name in the same directory (that is, the same path).

(2) DOS allows two or more files with the same name in different paths.

It is as if two sets of rooms are not allowed to have the same number in the same building, but the same number is allowed in two sets of rooms in different buildings.

The DOS system treats it as a special file when creating a subdirectory, so it is necessary to specify that a subdirectory also has three elements: drive letter, path, and subdirectory name. The general form of a catalog identifier is:

[drive letter "[path" (subdirectory name)

Paths and subdirectory names are also generally separated by a backslash ("\").

On the disk where the tree directory is established, there are many different directories, including root directory, first-level subdirectory, second-level subdirectory, …... One of the directories is called the current directory (for files, the current path) So how to identify the current disk and the current directory? If you execute the DOS command PROMPT $packs G (this command is introduced in the operating system), the first letter in the string before the prompt ">" is the current disk, and the string from the colon to the prompt ">" is the current directory.

This is the end of the introduction to the basic Concepts of DOS. Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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