The most frequent contact between us and computers is DOS. DOS is the abbreviation of English Disk Operating System, which means "Disk Operating System". As the name implies, DOS is mainly a disk-oriented system software. Simply put, DOS is a bridge between man and machine, and it is a layer of "shell" covering the hardware of the machine. With DOS, we don't need to know the hardware structure of the machine deeply, and we don't need to memorize those boring machine commands by rote. We just need to pass some DOS commands close to natural language. In addition, DOS can effectively manage all kinds of software and hardware resources and reasonably schedule them. All the software and hardware are doing their work in an orderly way under the monitoring and management of DOS.

(B) MS-DOS and PC-DOS

We often hear MS-DOS and PC-DOS when using DOS. For beginners, there is not much difference between the two. In fact, MS-DOS was produced by Microsoft, the king of software in the world, while PC-DOS was introduced by IBM, the king of computers in the world, with a slight modification to MS-DOS. Because of Microsoft's monopoly advantage in the world software industry, its product MS-DOS has become the mainstream operating system. As for PC-DOS, although it is not necessarily inferior to MS-DOS in function, MS-DOS's preconceptions are also helpless. Even if PC-DOS tries its best, it can't shake MS-DOS.

(3) DOS version

DOS launched its version 198 1, but its function is still very weak. 2.0 was introduced by 1983, which mainly increased the function of directory operation, and made file management go to a new level (we will introduce the concepts of directory and file when we explain DOS internal commands); 3.0 was introduced by 1984, and mainly supports 1.2MB 5.25-inch high-density floppy disk (1. X and 2. X only supports low-density disks) and large-capacity hard disks; 1987 introduces the most popular DOS 3.3, which mainly supports 3.5-inch floppy disks and networks. At this point, DOS has developed quite maturely. Although the subsequent versions (the latest version of PC-DOS is version 7.0, and the latest version of MS-DOS is version 6.22) are constantly introduced, there is no obvious kernel improvement, but many practical functions are added, such as disk detection, virus removal, hard disk expansion and so on.

(D) the significance of learning DOS well

It can be said that DOS 3.3 is a very important epoch-making version. Learning DOS 3.3 well can not only enhance the practical operation ability, but also lay a solid foundation for a better and faster transition to the new version. Therefore, this paper mainly focuses on MS-DOS 3.3, and appropriately mentions the functional enhancements in the new version.

Although Windows is in full swing at present, it tends to replace DOS, and Microsoft, the manufacturer of DOS, has stopped the further development of MS-DOS and is developing towards Windows integration in an all-round way. However, DOS is still an undeniable mainstream operating system (especially in China).

This section reviews the key contents: the function of DOS, the versions of MS-DOS and PC-DOS, and the importance of learning DOS. We realize the importance of learning DOS. Below, we will officially start learning DOS, starting with the most basic DOS startup.

Second, the beginning of DOS

1. What is a file?

We call a part of data with complete meaning stored on disk or CD-ROM a file. The meaning of data is extensive. The programs we write, the copied software, the images we make and so on. Can be called data, and data is stored on disk in the form of files. We can create, modify, delete, copy and move files.

With documents, it is natural to manage them, and naming is the best way. Each file has a name, called the file name, which consists of letters, numbers or characters, such as COMMAND.COM. File names can be divided into main file names and extended file names. Take COMMAND.COM as an example. COMMAND is the main file name, which mainly describes the content of the file, and COM is the extended file name, which mainly describes the nature of the file (here COM stands for command file). The decimal point in the middle is the separator between the main file name and the extended file name. DOS stipulates that the main file name cannot exceed 8 characters and the extended file name cannot exceed 3 characters. Because the decimal point is specially used as a separator, it cannot be used in the main file name and the extended file name. In addition, spaces are not allowed in the file name. The extension can be omitted, but the main file name must exist. So the following file names are all wrong, such as. EXE (unowned file name), ABC.BCD.COM (main file name contains decimal point) and ABC. DEFG (extended file name exceeds 3 characters).

In DOS, three extensions are defined as executable files, namely EXE, COM and BAT. The so-called executable file is a file that can execute the program by directly typing the main file name under DOS. Except for EXE, COM and BAT, all other files cannot be directly executed under DOS, which is called non-executive files.

2, the composition of DOS

DOS mainly consists of three basic files and some external commands. The concept of external command will be introduced later, and three basic files (also called system files) will be mainly explained here. These three basic files are MSDOS. System, IO. SYS and COMMAND.COM(IBM dos. COM, IBMBIO.COM and COMMAND.COM in the case of PC-DOS). Among them is MSDOS. SYS is called DOS kernel (see MSDOS. SYS is a very important file), which is mainly used to manage and start various components of the system to prepare for DOS boot. IO。 SYS(IO is the input &; The abbreviation of Output, which means "input and output", is mainly responsible for the basic input and output of the system, that is, the connection between DOS and various components. COMMAND.COM file (command means "command") is the interface between DOS and users. It mainly provides some internal commands of DOS, and can accept, judge and execute commands input by users. Whether a disk has the ability to start DOS depends on whether it has these three files. The disk containing these three files is called the startup disk. In addition, disks containing many DOS external commands are called system disks.

Finally, you should pay attention to the storage location of MSDOS. SYS and IO. SYS is limited and must be in the front of the physical location of the disk, otherwise it will lose its boot ability.

What is the starting point of DOS?

Every time we use the computer, we have to start DOS (also called boot), otherwise we can't operate the computer. After we turn on the power of the computer, the computer first performs a self-check, and then, if it starts from a floppy disk, the floppy disk will appear after a buzzer for more than ten seconds. Or a: \ > ; If you start from the hard disk, it will be much faster, and C> or C: \ > . A & gt、A:\ & gt； 、C & gt、C:\ & gt； It is called DOS prompt (DOS prompt is not static, and we will introduce the changes of DOS prompt in detail when explaining the internal command prompt). Its appearance shows that DOS has successfully completed the boot process, all kinds of software and hardware resources are under monitoring, and users can start to input commands.

(2) Preparation before startup

Since DOS is started, of course, the disk should have boot capability (that is, there are three system files). If you want to boot from a floppy disk, you should have a DOS boot disk or a system disk, insert the floppy disk (you must insert the A disk, and the location of the A disk of different computers may be different, so be sure to make clear in advance) to prepare for the boot. If you want to boot from the hard disk, just make the hard disk bootable.

(3) Classification of entrepreneurship

DOS startup can be divided into cold startup and hot startup. Cold start refers to the process of restarting the computer after cutting off the power supply. Hot start refers to the process of restarting without cutting off the power supply (that is, turning on the power supply). After a cold start, the machine must first perform a hardware self-check (the self-check time of different machines may be different, which mainly depends on the configuration of each component, such as the amount of memory, etc.). ) to determine whether the components are working properly. If the self-check passes successfully, it will enter the DOS startup state. There is no process of machine self-check in hot start, which is the main difference between them. So the speed of hot start is obviously faster than that of cold start. Because the hot start will not cut off the power supply of computer components, the life of hardware can be effectively extended. When there are no special circumstances (such as computer being attacked by virus, some software crashing during operation, blocking keyboard, etc.). ), try to use hot start.

The main method of cold start is to turn off the power supply, that is, turn it off. However, at present, there is a RESET (meaning "restart") button on the chassis of most packaged machines (or compatible machines). Its main purpose is to simplify cold start. Usually, the reset button is used as much as possible during cold start, which has less influence on the machine when it is turned on than when it is turned off (that is, pressing the power button), which is helpful to prolong the service life of the computer. It should be noted that the original machine (or brand machine), especially the imported machine, has almost no reset button (reset can be said to be the "patent" of the assembly machine). If you want a cold start at this time, you have to turn off the power. It should be noted that if the power supply is turned off for cold start, it must be turned off for at least 8 seconds to 10 seconds before it can be started again, so as to avoid damaging the components due to short interval. Hot start won't.