Ms dos version 3.0 interface image. History of the development of MS-DOS

The system software of each computer can be divided into two components - operating system (OS) and system software packages. Some of the system programs required by a computer are built into the machine, and specifically into a part of the computer called read-only memory (ROM). ROM programs are read-only. These system programs that provide control, assistance and necessary services to application programs are called basic input/output system (BIOS). Operating systems are examples of higher-level system programs. operating system - a set of programs that, interacting, jointly manage computer (system) resources and processes that use these resources when executing application programs.

Main OS functions:

Testing (checking the correct functioning) of hardware;

Deciphering and executing commands coming from the user (from the keyboard) or from random access memory;

Control of the operation of all devices and computer blocks;

Memory resource allocation;

Providing the ability for several users to work on one computer;

Protection of software from outside influence;

Maintenance of interruptions in hardware operation.

Purpose and characteristics of MS DOS. MS DOS versions; MS DOS composition;

MSDOS – Microsoft Disk Operating System, i.e. disk operating system from Microsoft. operating system MSDOS is the simplest operating system for IBMPC computers. It is used on all junior models of IBMPC and can be used on all older models of computers of the same type.

The first version of MS DOS had much more modest capabilities than modern operating systems. It was single-user, supporting only disk drives, a keyboard, and an alphanumeric display. But it was compact, had rather modest requirements and performed the necessary minimum functions for users and programs. Over time, many changes were made to MS DOS:

Support for new devices (hard drive, CDs, extended memory, etc.) has been added, and the ability to support any other devices using software drivers has also been provided;

Enabled support for hierarchical file structure on floppy disks and hard drives;

Support for national keyboards and alphabets is provided;

Numerous new user features are included.

MS DOS remained a single-tasking OS;

It turned out to be impossible to build into MS DOS reliable means for protecting data from unauthorized access and organizing collective work with data;

DOS programs can only be executed within the first MB of memory, and the rest of the memory can only be used for data storage.

OVERVIEW OF MS DOS VERSIONS

Versions 1.x : Very similar to OS CP/M. Only single-sided floppy disk format with a memory capacity of 160 KB (8 sectors, 40 tracks, sector size 512 bytes) was supported. Starting with version 1.25 (PC DOS 1.0), which appeared in May 1982, a double-sided floppy disk format with a memory capacity of 320 KB was introduced.

Versions 2.x : March, 1983 Additional features: working with hard drives(HDD); hierarchical structure file system; I/O redirection tools (borrowed from UNIX); the concept of installable peripheral device drivers, which made it possible to quickly adapt the OS to various hardware configurations; 360 KB floppy disk format (9 sectors, 40 tracks, sector size 512 bytes)

Versions 3.x : August, 1984 Additional features: 1.2 MB floppy disk format,

3.5" floppy disks (720 KB format) (starting from version 3.2), partitioning the HDD into logical disks (up to 32 MB in size), which made it possible to use HDDs larger than 32 MB in size, improved support for national character sets. Support for computer networks (weak , starting from version 3.1), commands (programs): LABEL, ATTRIB, commands (programs): XCOPY, REPLACE (starting from version 3.3),

MS DOS 3.3 is by far the most widely used on the IBM PC XT and the IBM PC AT-286 with a memory capacity of no more than 640 KB.

Versions 4.x : November, 1988 Additional features: support for graphic Video Adapters EGA, VGA, volume logical drives- more than 32 MB, support for the LIM/EMS standard, which allowed certain parts of MS DOS to be loaded into additional memory,

Dos-Shell shell program. Despite this, MS DOS versions 4.x are not widely used.

Version 5.0 : July, 1991 Additional features: efficient use of RAM, additional utility programs, the ability to load the MS DOS kernel into HMA memory (High Memory Area) on the IBM PC AT-286 and higher, the ability to load peripheral device drivers into UMB memory on IBM PC AT-386 and higher,

up to 620 KB of address space (0-640 KB) of RAM is allocated for application programs,

HDD support up to 2 GB, 2.88 MB format for 3.5" floppy disks

Version 6.0 : March, 1993 Additional features: efficient use of RAM, additional utility programs, software for optimizing the file system on logical disks (DEFRAG), commands (programs) that have lost their relevance have been removed, special. MEMMAKER program - optimization of the location of resident programs in RAM, multi-configuration files ONFIG.sys, virus protection system (weak), increasing available disk space (DoubleSpace),

means for regulating PC power consumption (LapTop, NoteBook)

Version 6.2 : October, 1993. All improvements are in the area of ​​increasing the reliability of working with data at the file system level. Additional features: increased efficiency of existing commands (programs), CD-ROM caching, rejection of DoubleSpace without loss of information, identification and bypass of physical defects of HDD and FDD, identification and elimination of defects in the file system, including “compressed” DoubleSpace, step-by-step execution of any *.bat file, including AutoExec.bat,

What does the MS-DOS operating system consist of?

The MS-DOS operating system consists of many different files. They include the actual operating system files IO.SYS, MSDOS.SYS and the command processor COMMAND.COM. In addition to these three files, which represent a working MS-DOS kernel, the operating system distribution includes files of so-called external commands, for example FORMAT, FDISK, SYS, drivers for various devices and some other files.

The IO.SYS file contains the extension basic system input/output and is used by the operating system to interact with the computer hardware and BIOS.

The MSDOS.SYS file is in a sense a set of interrupt handling programs, in particular the INT 21H interrupt.

The COMMAND.COM command processor is designed to organize a dialogue with the computer user. It analyzes commands entered by the user and organizes their execution. The so-called internal commands - DIR, COPY, etc. are processed by the command processor.

The remaining operating system commands are called external commands. External commands are so named because they are located in separate files. Operating system external command files contain utility programs for performing a variety of operations, such as formatting disks, sorting files, and printing texts.

Drivers (usually files with the extension SYS or EXE) are programs that support various hardware. The use of drivers easily solves the problems of using new equipment - just connect the appropriate driver to the operating system.

Application programs interact with the device through the driver, so they will not change when the hardware changes. For example, new disk device may have a different number of tracks and sectors, different control commands. All this is taken into account by the driver, and the application program will work with the new disk as before, using DOS interrupts.

The operating system files IO.SYS, MSDOS.SYS and COMMAND.COM must be written to a specific location on the disk. They do not need to be copied to other directories on the disk.

The loading process is carried out as follows. First, the system start record is loaded into memory, then - system files IO.SYS, MSDOS.SYS and COMMAND.COM.

When the machine is turned on (or the system is restarted), control is transferred to the ROM program (memory read only). The program checks the correct structure of the operating system startup record on the system disk. If the entry is found and does not contain errors, then it is loaded into memory and receives control.

The start entry checks whether the IO.SYS and MSDOS.SYS files are the first files on the disk. If the test result is positive, then the files are loaded into memory, and the free section with the lowest address is selected. Control is then transferred to the initialization module of the IO.SYS file. If the files are written in a different location or are not on the disk, a message appears on the screen:

Non system disk replacement and press any key

The initializing module transfers control to the MSDOS.SYS file, which determines the initial parameters of the disk buffer and data control block area used when executing service programs. File programs also determine the status and initialize the computer's electronic equipment. After this, control returns to the initializing module IO.SYS.

The initializing module checks for the presence of the CONFIG.SYS file in the root directory of the system disk. If a file is found and contains data about available drives, then the specified drives are stored in memory.

Files One of the main responsibilities of MS-DOS is the maintenance (storage, creation, destruction, etc.) of files. A file in MS-DOS is similar to any file. This is a set of interrelated data located in a specially designated place. Unlike ordinary documents stored in special archive folders or safes, MS-DOS files are stored on disks. When a file is processed, it is loaded into the machine's RAM. Both loading into memory and storing files are functions of the operating system.

File identification Every file in MS-DOS must have a name. The file name can be simple or complex. A complex name consists of a base (simple) name and an extension. The file is recognized by the operating system by its name. The names of some files, for example those on the system floppy disk, are predefined. They are reserved by the operating system. The names of the remaining files are assigned by the user. Usually they try to come up with a name that reflects the purpose of the information inside the file. The extension is used to indicate the file type, for example, text or data file. It can also serve to identify files with information similar in meaning, for example, to differentiate files with personal and business correspondence. When a file is written to disk, its name is automatically placed in an area of ​​disk memory called a directory (or directory).

File serving in MSDOS The file management system in MS-DOS is built on the use of directory (or directory) data on the disk. A directory is an area of ​​memory on a disk that is allocated during the formatting process. A directory is a table where data about files stored on disk is entered. Each file in the directory corresponds to one entry. The directory entry includes the following information: the full name of the file (name and extension), the date and time of its creation or last modification, the amount of memory occupied in bytes, as well as some additional information used when servicing the file by the operating system .

Tracks and sectors In order for data to be written to a disk, its surface must be structured - i.e. divided into sectors and tracks. TRACKS are concentric circles covering the surface of the disk. The track closest to the edge of the disk is assigned the number 0, the next one - 1, etc. If the floppy disk is double-sided, then both of its sides are numbered. The number of the first side is 0, the number of the second is 1.

Each track is divided into sections called sectors. Sectors are also assigned numbers. The first sector on the track is assigned the number 1, the second - 2, etc. Typically a sector takes up 512 bytes.

Hard disks A hard drive consists of one or more round platters. Both surfaces of the plate are used to store information. Each surface is divided into tracks, tracks, in turn, into sectors. Tracks of equal radius form a cylinder. Thus, all zero tracks make up cylinder number zero, tracks number 1 make up cylinder number 1, etc.

File and directory allocation table The FORMAT command creates a file allocation table (FAT) and disk directories. Both of these structures are closely related to the organization of access to files. There are two copies of FAT on each drive. This table is of exceptional importance when serving files, so if the first copy of FAT is lost, the system gains access to the second.

On a standard floppy disk with 8 sectors per track, FAT occupies 1 sector. On a standard floppy disk with 9 sectors, 2 sectors are allocated per track for the table.

Directory structure A directory is a table describing the contents of a disk. Each file in the table corresponds to one entry. A record occupies 32 bytes, divided into 8 sections or fields. Each field records information used by the system when servicing the file.

System file maintenance MS-DOS provides two file serving technologies. The first was developed during the creation of versions 1.X. This technology is based on the use of data structures called file control blocks (FCB). At that time, the vast majority of computers ran the CPM operating system. FCB blocks provided compatibility MS-DOS files with the files of this system. During the development of MS-DOS versions 2.X, when a hierarchical file organization structure was proposed, a second technology for maintaining them was developed. It is based on the use of references to the file control record and does not require the organization of an FCB. After this technology was tested in the operating room UNIX system, it has become widespread.

Memory organization

Memory consists of a large number of individual elements, each of which is designed to store a minimum unit of information - 1 byte. Each element has a unique numeric address. The first element is assigned address 0, the second - 1, etc., including the last element, whose address is determined by the total number of memory elements minus one. Usually the address is specified by a hexadecimal number (in the text, hexadecimal numbers are marked with a capital “H”, for example, 10H).

Segments A computer's processor (CPU) divides memory into blocks called segments. Each segment occupies 64 K and each segment has a unique numeric address. The processor has four segment registers. A register is an internal structure designed to store information. Segment registers are designed to store the addresses of individual segments. They are called CS (Code Segment), DS (Data Segment), SS (Stack Segment) and ES (Spare Segment). In addition to those indicated, the processor has 9 more registers. At this point, the IP (instruction pointer) and SP (stack pointer) registers should be noted. The CS and IP registers paired together make up the long address of the instruction that will be executed next. The SS and SP registers in pairs make up the long stack address.

Memory access Access to memory cells is carried out by connecting the contents of a segment register with the contents of one or another register. In this way, the address of the required memory area is determined. For example, the address of the next instruction is determined by the contents of the CS and IP registers (written “CS:IP”). After a command is executed and removed from memory, the contents of IP are changed so that the CS:IP registers contain the address of the command that will be executed after this one. The method of combining registers to determine the address of a memory cell does not impose restrictions on the amount of available memory. The upper limit depends on the physical structure of the memory (i.e., the total number of cells). The first versions of MS-DOS were developed for the Intel 8088 CPU. Each register of this processor is designed to store a 16-bit number. That is, the 8088 CPU combines the contents of a segment register (say CS) with the contents of another register (say IP) to produce a 20-bit memory address, which limits available memory up to 2xx20 bytes or 1 MB. Later, improved versions of MS-DOS appeared and, accordingly, improved CPU processors 80286 and 80386, allowing access to cells located beyond the boundaries of the first MB of memory. However, the 1 MB limit has not yet been overcome (at least in version 3.3), which is one of the main drawbacks of the operating system.

Memory access is organized by connecting the contents of one of the segment registers with the contents of one of the remaining registers. The value of the segment register is called the segment address. The value of the remaining registers in this case is called the relative address of the memory cell (from the beginning of the segment) or its short address. Thus, the byte address is calculated by multiplying the segment address by 16, and adding the short address to the resulting value.

Segment registers Segment registers are used to identify a memory segment. A segment is a contiguous block of memory, 64 K long. Segment registers are used in combination with a pointer register or index registers and in this case identify a specific memory cell.

There are four segment registers in total. The CS register is usually used to identify the memory block in which the program code is stored. The DS register identifies the memory location in which the data of this program is located. The SS register is used to organize access to the stack. (A stack is a temporarily distributed memory area that provides the “MS-DOS-application program” interface). Register ES - additional (or spare) segment register. It is assigned a variety of functions, some of which are discussed below.

Stack registers There are two stack registers. They are used in combination with the SS register and determine the location of the stack. The SP register is called the start of stack pointer, and in combination with the SS register identifies the first byte of the stack. The BP register is called the stack base pointer and, in combination with the SS register, identifies the last byte of the stack.

Index registers There are also two index registers. The SI and DI registers are used in combination with one of the segment registers and determine the location of a specific memory cell. The SI register is usually combined with the DS register, the DI register with the ES register.

General purpose registers General purpose registers include registers AX, BX, CX and DX (there are four of them). These are multifunctional registers.

The IP instruction pointer register is usually used in combination with the CS register and specifies the address of the next instruction.

Status flag register

The flags register usually contains nine processor status flags (each flag occupies 1 bit). These flags determine the result of specific operations performed under MS-DOS. Memory Registers A memory register contains 2 bytes of data (or 16 bits). In reality, general-purpose registers are single-byte. Thus, the AX register includes the AH register (which makes up the high byte of the AX register) and the AL register (which makes up the low byte of the AX register). Similarly, the BH, BL, CH, CL, DH and DL registers are single-byte.

MSDOS Drivers The two most important components of a computer's electronic hardware are its central processing unit (CPU) and its memory. The remaining components (disk drives, keyboard, displays, printers, etc.) are external to the computer. These external components of electronic equipment are called PERIPHERAL DEVICES or simply DEVICES.

The connection between the machine and the peripheral device is carried out in a strictly defined order. Each peripheral device in the operating system has a corresponding program that is responsible for its contact with the computer. These programs are called DRIVERS.

Application of drivers One of the main functions of the operating system is to provide a group of functional drivers available to system and application programs. If a running program needs contact with a peripheral device, it tells the operating system which device it needs, and MS-DOS provides it with the appropriate driver.

Character-by-character and block-by-block data transmission devices Character-by-character data transmission devices transmit information one character at a time. These devices include serial and parallel adapter ports and displays. In MS-DOS, each of these devices has a specific name (name). The MS-DOS driver can control only one character-by-character device. Block-by-block data transmission devices send information across blocks. Each block is typically 512 bytes. These devices include floppy disk drives, hard disk drives, and other storage devices. Block transfer devices do not have a specific name. The MS-DOS driver can serve several devices block by block

Interrupts An interrupt is a signal coming from software programs or generated by electronic equipment. An interrupt signal alerts the processor (CPU) to perform certain functions. For example, when you press any key, an interrupt signal is generated from the keyboard (i.e., from the electronic equipment), warning the processor about entering data from the keyboard.

Each type of interrupt corresponds to a specific serial number (a keyboard interrupt, for example, is designated number 9). Using this number, the processor distinguishes which handler needs to be called to process the interrupt signal. By convention, interrupt numbers are presented in hexadecimal format.

Interrupts numbered 20Н-2FH are reserved for system use. This means that application programs designed to interact with the system software can access these interrupts only in special cases that are defined by the operating system. Most often, the 21H interrupt is used programmatically - the function manager.

Function Manager Interrupt 21H is called “function manager”. The function manager is responsible for doing most of the work in MS-DOS. His responsibilities include providing access to system functions. Each function performs a specific task, such as opening a file, displaying a character string on the display screen, allocating a block of memory, or displaying the running version of MS-DOS. The functions are also differentiated by numbers.

To programmatically access a system function, you must do the following: (1) write the number of the corresponding function in the AN register; (2) write the parameters necessary for the function to operate in the appropriate registers; (3) cause interruption of 21H. When accessing interrupt 21H, control is transferred to MS-DOS. The operating system uses the value of the AH register to determine which function should be executed. Then the parameter values ​​are read from the remaining (completely defined for each function) registers, after which the required function is executed. MS-DOS places the parameters returned by the function into the appropriate registers and returns control to the calling program. The program looks at the registers and analyzes the result of the function.

Reserved functions Some functions are marked as “reserved for system use.” These functions are used by the operating system, but IBM and Microsoft refuse to consider them in the official literature. Thanks to the efforts of programmers, the purpose of some of them became known. Users who use these functions often refer to them as “officially undocumented” rather than “reserved”.

Error code Many functions of MS-DOS versions set the current processor flag and return an error code in the AX register if an error occurred while calling the function. From special tables you can find out the cause of the error.

The concept of system, current and logical disks; DOS prompt.

Logical drive or volume (English volume) - Part long-term memory computer, considered as a single whole for ease of use.

When DOS is ready to interact with the user, it displays invitation, for example A> or C:\>. This means that DOS is ready to receive commands. When the user is interacting with a program other than DOS, then there is no DOS prompt. However, most programs communicate with the user not using commands, but through menus, requests, pressing certain key combinations, etc. The DOS prompt usually contains information about the current directory. But sometimes it also includes information about the current time of day. You can change the invitation type using DOS commands Prompt.

The concept of the DOS kernel, the main functions of kernel modules;

The MS DOS kernel implements the MS DOS system, which is a special program supplied by Microsoft that includes a set of hardware-independent utility programs called system functions. These include: 1. File and record management. 2. Memory management. 3. Character-oriented input/output device. 4. Generation of other tasks. 5. Access to real time clock. The MS DOS kernel is read into memory during system initialization from the MSDOS.SYS file located on the boot disk; this file is distinguished by the hidden and system attributes.

Purpose of files config.sys And autoexec.bat;

The config.sys and autoexec.bat files play a major role in establishing the DOS configuration. When DOS boots, it reads the config.sys and autoexec.bat files from the root directory of the boot disk and executes the commands contained there. The config.sys file is a text file that contains special commands for setting up the DOS configuration: connecting various drivers, determining the size of the DOS system tables, etc. commands specified in the config.sys file are executed in the process bootstrap DOS.

When the config.sys file is completed, it is automatically executed batch file autoexec.bat, if it is present in the root directory of the boot disk. As a rule, the autoexec.bat file contains commands for launching resident programs and other programs that are advisable to run every time DOS boots, as well as commands for setting DOS environment variables, specifying the list of directories in which programs to be launched are searched, and setting the DOS prompt format.

We are accustomed to the fact that when working with a computer, we see on a high-definition display a comfortable “desktop” surface with “folders” and “documents” laid out on it. Each executed program and each document is assigned separate window, and we control all this using a hand-held manipulator, which for some reason is called a “mouse”. Nothing prevents us from launching several programs and switching between them, working simultaneously with several documents different types. We don't think about the fact that this type of computer-user interaction was developed only three decades ago, and that it is called a graphical user interface. (Not to mention that today it is extremely easy to connect a computer to various types networks and supports a huge number of types of external devices.)

And of course we don’t think about the fact that for only thirty years users controlled the computer using commands entered from the keyboard, and the computer - more precisely, the MS-DOS operating system - responded to erroneous commands by producing obscure text messages in poisonous green letters, for example :

Not ready reading drive A
Abort, Retry, Fail?

Bad command or file name

Programs had to be loaded one at a time (MS‑DOS did not have multitasking capabilities), they had a lot of compatibility problems and a very heterogeneous user interface. But those who didn't like it could return to the typewriter and ink drawing. And there were fewer and fewer such hunters - the ability to save documents in the form of electronic files and then reuse and modify them, rather than reprint them all the time as carbon copies, opened up the broadest prospects.

To understand why the MS-DOS operating system was exactly the way it was, how it became a kind of springboard for Microsoft Windows, and why, in its various guises, it existed for two whole decades, let’s move back another decade, to 1971.

Before MS-DOS

In 1971, Intel, commissioned by the Japanese company Busicom, released integrated circuit 4004 - the first microprocessor functionally similar to the modern one central processor, underlying any computer, but much less powerful - it was four-bit, i.e. could only process four-bit binary numbers, from zero to 1111 (decimal 15), and had a clock speed of less than 1 MHz. Just a year later, the first eight-bit microprocessor, the 8008, appeared, and the 2 MHz 8080 microprocessor, released by Intel in 1974, was already so powerful that it could be used to build a small computer. This is what MITS did, which released the world's first PC, Altair 8800, in 1975.

It was followed by PCs from other companies, which also used eight-bit microprocessors from Intel and other manufacturers - Motorola, Zilog. Unlike professional computers working with UNIX, PCs used the CP/M (Control Program for Microcomputers) operating system from Digital Research - the first OS to run on PCs from various manufacturers. To others software, which worked on almost all PCs that existed at that time, was a language translator Basic programming, released by the young company Microsoft.

The Rise of MS-DOS

In 1980, IBM decided to enter the PC market, and in 1981 the IBM Personal Computer model was released, created by the IBM entry-level systems department under the leadership of Philip Donald Estridge - the great Don Estridge (1937-1985), now revered as a father IBM PC. To reduce time and costs as much as possible, the developers used open architecture. The IBM PC was designed using independently manufactured components. The base model IBM PC had 64 KB of RAM, expandable to 256 KB. The brain of the IBM PC was the new 16-bit microprocessor 8088 from Intel. Hardware documentation and software specifications were published.

When IBM approached various software firms about its new PC project in October 1980, Microsoft could not offer IBM its own OS. However, Digital Research only had the CP/M-80 available for 8-bit computers. While Digital Research was working on the 16-bit CP/M-86, Microsoft acquired the rights to the 16-bit 86-DOS system from Seattle Computer Products.

One of the important qualities of 86‑DOS was the easy portability of programs from the CP/M‑80 environment. It also borrowed many of the CP/M commands, such as REN (rename file), DIR (display directory contents), and TYPE (display file contents). A significantly revised version of 86‑DOS was called MS‑DOS 1.0. In August 1981, deliveries of IBM PC computers began with this OS under the name PC‑DOS 1.0. In addition, Microsoft received the right to sell licenses for MS‑DOS to other PC manufacturers.

The abbreviation DOS (Disk Operating System) emphasized the main purpose of this operating system - to provide disk I/O control. MS-DOS did not have built-in support for tape drives or local area networks. The main thing it provided was working with files. For ease of use of files, MS‑DOS allowed them to be given names up to eight characters long, with a description (extension) of up to 3 characters, for example DOCUMENT.TXT or READ.ME.

MS‑DOS 1.0, quite progressive compared to CP/M, used more advanced methods for managing disk data and had a wide range of commands for utility programs. Since the original IBM PC came with 160-kilobyte floppy disk drives, PC-DOS 1.0 only supported such media. Other PC manufacturers did not adopt PC-DOS until PC-DOS 1.1 was released in May 1982, allowing it to work with 320 KB floppy disks. That's when Microsoft was able to exercise its right to sell licenses for MS‑DOS - a month later the same version of the OS was released under the name MS‑DOS 1.25, and it began to be used by Texas Instruments, Compaq Computers and other companies that began manufacturing IBM PC-compatible computers.

MS‑DOS 2.0 (March 1983) supported 360 KB floppies and 10 MB hard disks(especially for the new IBM PC XT computer) and provided the ability to sort files into directories. It was then that the global boom in the production of IBM PC-compatible computers began - such respectable companies as Tandy, Hewlett-Packard, Digital Equipment Corporation and others joined the list of manufacturers of these machines. MS‑DOS 2.11 became the base OS for the products of many companies - the most stable implementation of the second generation of MS‑DOS.

MS‑DOS 3.0 (August 1984) was aimed at new model IBM computers - IBM PC AT - the first computer based on the Intel 80286 microprocessor, with a 5.25‑inch high-density floppy drive (for 1.2 MB floppy disks) and a 20‑MB hard drive. MS‑DOS 3.2 (December 1985) supported 3‑inch 720 KB floppy disks and logical hard sections disks up to 32 MB. The system continued to evolve, adding more and more capabilities to support national currency and time images, character tables, and keyboard layouts.

The popularity of the IBM PC platform also grew, there were more manufacturers of IBM PC-compatible machines, and the number of software developers for the IBM PC exceeded all conceivable limits. In 1986, an IBM PC-compatible computer from Compaq Computer, based on the 80386 microprocessor, had already appeared. The following year, IBM also had a computer with an 80386 microprocessor - PS / 2 Model 80. MS‑DOS was not able to fully exploit the capabilities of the new computers. So, if computers with an 8086 microprocessor were produced with no more than 640 KB of RAM, then on the 286th computer it was theoretically possible to install up to 16 MB of memory, and on the 386th - up to 4 GB. MS‑DOS could never use more than 640 KB of memory.

However, the growing market demanded intensive production of IBM PC-compatible machines, even more intensive improvement of MS-DOS, and perhaps even more intensive release of professional applications for the IBM PC and MS-DOS. One of the main requirements was compatibility: all new versions of MS-DOS had to work successfully with programs released for older versions of MS-DOS.

Therefore, in MS‑DOS 3.3 (April 1987) there was nothing fundamentally new, but everything old was improved. In particular, version 3.3 supported the new 3‑inch 1.44 MB floppy disks. MS‑DOS 3.3 became the most important stage in the history of MS‑DOS development, the following versions MS‑DOS 4.0 and MS‑DOS 4.01 (1988) did not attract much attention from buyers. Most IBM PC users remained faithful to MS‑DOS 3.3.

The emergence of Windows

As we have already noted, MS‑DOS had a very primitive user interface: in order to load a program or perform other operations, the user had to type commands on the keyboard. For example, the command to copy from the DOC\WORK directory of drive C: to drive A: all files and directories, except those that are already there, looks like this:

REPLACE C:\DOC\WORK\*.* A:\ /S /U

In 1985, Microsoft released the first version of Windows, a graphical MS‑DOS shell that offered the user a windowed interface. To take full advantage of Windows, the program must be designed specifically for Windows.

The IBM PC-compatible computers that existed at that time, however, did not have enough power to ensure the full functioning of the graphical environment. Therefore, the Windows that was made in 1985 looked rather pale. But Microsoft continued to invest in Windows. In 1987-1988 Various implementations of Windows/286 and Windows/386 (Windows 2.x) appeared.

Designed to run on appropriate microprocessors, they were already quite functional. Finally, in May 1990, an event occurred that largely determined the current state of the hardware and software market for IBM PC-compatible computers.

Windows 3.x

Windows 3.0, released in May 1990, booted under MS-DOS, but made you forget about MS-DOS immediately. Access to the entire amount of computer memory was carried out through the MS‑DOS driver HIMEM.SYS and special system"MS‑DOS extensions". This led to a qualitative leap - a completely graphical window interface combined with multitasking capabilities. Windows multitasking did not allow you to control the work of programs as flexibly as OS/2 multitasking, but it required less memory. On computers with an 80386 microprocessor and higher, Windows 3.0 worked with virtual memory, that is, it used part of the disk as an extension of RAM.

To launch programs, the Program Manager application was used. To be able to organize and store launch icons for a large number of applications, the developers made the File Manager multi-window. For operations with files and disks, Windows 3.0 included a multi-window File Manager program - File Manager, which allowed many operations with files using the drag-and-drop method.

MS-DOS logo from the MS-DOS 6.0 box

MS-DOS mode icon from Windows 95 operating system

The range of services provided by Windows has led to the fact that all promising programs began to be developed taking into account the requirements of Windows. MS-DOS was now primarily expected to be a strong support for Windows, and in June 1991, MS-DOS 5.0 was released, designed to work better with Windows 3.0. It included, for example, a new version of HIMEM.SYS. To illustrate the benefits of multitasking, MS‑DOS 5.0 shipped with the MS‑DOS Shell with a program switching subsystem borrowed from Windows 3.0.

In April 1992, Windows 3.1 went on sale. From now on it is called the operating system. Strictly speaking, this environment could not function independently, without MS‑DOS. But this does not change the state of things. A little later, Windows 3.1 for Workgroups was released to work with peer-to-peer local networks, and a year later - Windows 3.11, almost identical to Windows 3.1, and Windows 3.11 for Workgroups. These versions of Windows have many improvements over Windows 3.0.

In 1993–1994 Several new versions of MS‑DOS were also released. The most significant feature of MS-DOS 6.0 (April 1993) was the availability of a large collection of original and licensed utilities, including Microsoft DoubleSpace for increasing the usable capacity of disks through dynamic data compression. In MS‑DOS 6.2 (October 1993) Microsoft program DoubleSpace was improved; from version MS‑DOS 6.21 it was removed due to legal conflicts with Stac Electronics, the manufacturer of a similar program called Stacker, and in version MS‑DOS 6.22 (both 1994) it was replaced by DriveSpace, which did not cause any criticism from the company Stac. And this was the last standalone version of MS‑DOS.

Windows 9x

Subsequent versions of MS-DOS were included with the latest versions of Windows.

The partially 32-bit operating system Windows 95, released by Microsoft in the late summer of 1995, had internal MS-DOS 7.0, it could be used to support programs that were incompatible with the new version of Windows, but by default it would immediately load on users' computers. graphical interface.

Why was it so important to lure users away from MS‑DOS? The new generation of Windows provided higher reliability and more stable and consistent application concurrency than Windows 3.1. Windows 95 made better use of memory and disks, and also allowed file names of up to 255 characters. The system supported the specification automatic settings Plug and Play hardware that automatically detects and configures most existing hardware for IBM PC-compatible computers. Windows 95 worked with all types of gaming and multimedia devices that existed at the time of the OS's release.

Windows 95 was the first system that, on the one hand, was designed to run 32-bit programs, and on the other, worked with 16-bit Windows 3.1 programs and almost any MS-DOS program. The ultimate goal was to get rid of 16-bit code and completely move the entire market to 32-bit applications and operating systems. It was for this purpose that the branch of Windows NT developed in parallel - modern, fully 32-bit operating systems for business.

During 1995-1998 Microsoft constantly updated Windows 95, and in 1998 it released Windows 98, which had an improved interface, a new file FAT system 32, and supported a unified device driver model for Windows and Windows NT ( Windows Driver Model), as well as new types of equipment, including the Universal Serial Bus (USB) port, etc. The integrated version of MS‑DOS was numbered 7.1.

The two thousandth versions of Windows for home (Windows Millennium Edition, or Windows Me) and Windows for business (Windows 2000) were very similar in appearance. At the same time, Windows 2000 almost provided the necessary flexibility in using a variety of software (including computer games and multimedia) and in selecting equipment, and MS-DOS was almost excluded from Windows Me - only the boot loader remained with internal number version 8.0.

With this, the adventures of MS-DOS and the history of two parallel branches of Windows ended, and a new era began - next version Microsoft's operating system became Windows XP.

In conclusion, we note that at different times different companies released their own versions of MS‑DOS-compatible operating systems. These were not only versions of DOS intended by manufacturers for installation on PCs of their own production, such as Compaq DOS, Zenith DOS or early versions PC‑DOS from IBM. Individual versions DOS was released for general sale to compete with Microsoft's MS-DOS. These include DR DOS from Digital Research, Novell DOS 7.0 ( latest version DR DOS, released after Digital Research was acquired by Novell), later versions of IBM PC‑DOS, PTS‑DOS from the Russian company Phystech-Soft, etc.

And most importantly. The importance of the MS-DOS operating system is difficult to overestimate. It controlled computers with microprocessors with a clock frequency of less than 5 MHz, a RAM capacity of up to 640 KB and with hard drives so small that even a single photograph taken by a modern professional camera would not fit. Today we work on personal computers with 32- and 64-bit architecture, the microprocessor frequency of which is measured in gigahertz, the amount of RAM is measured in gigabytes, and the hard drive capacity is hundreds of gigabytes, but it is the reliable, unpretentious workhorse MS‑DOS that has pulled out the entire computer revolution. Millions of people became users and programmers of personal computers with this operating system.

Kamill Akhmetov
Microsoft Technology Officer

Good day.

If you are interested in the DOS operating system, what it is, by whom and in what cases it is used, you have come to the right place. In my article you will find answers to these questions and find out how DOS differs from the familiar and beloved Windows system.

Acquaintance

This abbreviation stands for English language as Disk Operating System, or in our opinion - a disk operating system. It includes a whole family of PC operating systems that involve the use disk drives, that is, hard drives and floppy disks.

The first version was released by Seattle Computer Products in 1980. Later, the product was bought by Microsoft Corporation, signing a contract with IBM that included the development of an operating system for a new model of computers from this company.

Nowadays DOS is rarely found, except for working with outdated equipment or programs written a long time ago. It was popular during the advent of computers. Although there are extenders that allow you to fully use this product today.

Comparison with Windows

In order for you to better understand the essence of our conversation, I will make a comparison with Windows, since this system is one of the most popular. I won’t go into the weeds, but I’ll just say the main thing.

In the 80s of the last century, computers were not as compact as they are now, but were large electronic computers. Despite their size, their functionality was not very diverse. Therefore, a single-tasking 16-bit one with a simple interface was enough for them.

Didn't understand the last sentence? This means that in DOS you cannot work in multiple windows and programs, as Windows allows, which, by the way, has , and therefore can quickly process more commands.

The appearance of DOS is much simpler than that of beautiful and colorful Windows with many different icons and buttons.

The shell of the old brother is similar to command line Windows. That is, it did not have a graphical interface.

Also in mind rapid development technology, disk system does not cope well with current sound, video cards and other hardware. It also does not involve means of control and protection against viruses, since at the time of its popularity, they essentially did not exist. While Windows is adapted to modern requirements.

In favor of disk operating systems

From the point of view of the average user, Windows wins due to the above advantages. However, there are times when none of them matter. For example, for an accountant who does not need to switch between windows, it is more convenient to work in MS-DOS. Since the interface allows you to preserve your vision, or rather strain it less.

And many experienced programmers prefer outdated system. Because its simplicity allows you to completely take control over it into your own hands. To perform basic functions, it only needs a few light files, while in Windows there are quite a lot of them and all the most important things, especially , are reliably hidden from the user.

DOS components

This OS includes:

• Basic input/output system (). Embedded in permanent memory your hardware. Needed to check the functionality of the hardware when starting the computer and calling the initial DOS startup block.
• Boot Record block is a lightweight program (no more than 512 Bytes). After the BIOS, she loads two more modules to finally turn on the system.
• BIOS expansion module (IO.SIS). Its functions include setting up the OS configuration and installing drivers.
• Interrupt handling module (MS DOS.SYS) - maintains the file system (FAT with a limit of 8 characters for file and directory names), and is also responsible for data input/output.
• Command processor (COMMAND.COM) - processes tasks that you give.

• Built-in drivers for the operation of a mouse, keyboard, drive, etc.
• Utilities necessary to perform various service functions (format a disk, etc.).

I think the above information is sufficient for general information.

Have a good mood!

DOS stands for Disk Operating System. In just a few years, the DOS system has gone from a simple boot loader to a universal operating system for personal computers built on the Intel 8086 microprocessor.

Let's start counting the history of DOS in 1973 - it was in this year, so far from us, that Gary Kildall wrote a simple operating system in the PL/M language he created (Programming Language/Microprocessor). He called it CP/M - Control Program/ Monitor, or Control Program for Microcomputer. By the mid-70s, the SR/M-80, the rights to which belonged to Digital Research, became the most popular system for computers based on Intel 8080 and Zilog Z-80. This system provided access to a variety of application software ( word processors, database administrators, etc.).

due to delayed release new version of this system (CP/M-86) in April 1980, Seattle Computer Products, which manufactured computers based on 8086 processors, decided to use their own operating system, which was eventually (by August of the same year) written by Tim Peterson . This operating system was called QDOS (Quick & Dirty Operating System), but then renamed 86-DOS. To make the transfer process easier application programs from the 8-bit CP/M-80 system to the new 16-bit environment of the 86-DOS system, the latter was initially built so that it could imitate all the functions and types of operations of the CP/M-80. As a result, the structures of file control blocks, program segment prefixes and executable files in the 86-DOS system are almost identical to the structures of CP/M-80.

Programs that existed in CP/M-80 could be easily converted (by processing files source programs using a special translator) and then run it in the 86-DOS system either immediately or by performing simple manual editing. Due to the fact that 86-DOS was marketed as the proprietary operating system of the Seattle Computer Research family of computers with the S-100 interface based on the Intel 8086, in general this approach had little impact on the state of affairs in the world of personal computers. Other vendors of Intel 8086-based computers, forced for obvious reasons to use a competitor's operating system, eagerly awaited the release of Digital Research's CP/M-86 system.

In October 1980, IBM invited computer software firms to begin searching for an operating system for a new family of personal computers. Microsoft could not offer its own operating system (with the exception of the standalone version of Microsoft BASIC), but in July 1981 it bought the right to use the 86-DOS operating system from Seattle Computer Products, after which it entered into a contract with IBM, committing to develop the operating system for a new model of personal computers produced by the company. By the way, as a result of this transaction, Seattle Computer Products received a license to use and sell programming languages ​​and all versions of the operating system for the 8086 microprocessor developed by Microsoft.

At the end of 1981, when new computer The IBM PC gained widespread popularity (IBM 5150 PC: 4.77-MHz Intel 8088 CPU, 64KB RAM, 40KB ROM, 5.25-inch floppy drive - "only" $3000), its operating system was a modified version of the 86-DOS system, called the PC -DOS 1.0. Soon after the release of the IBM-PC, personal computers, “PC-like” (PC-compatible). The operating system of these computers was called MS-DOS 1.0 - Microsoft Corporation made available to the companies producing these machines an exact copy of the PC-DOS operating system - the now widely known MS-DOS.

The only major difference between these systems was what is called the "system level", that is, each machine had to buy its own operating system. The distinctive features of each system could only be identified by a system programmer, whose duties included the work of “tailoring” the operating system to a specific machine, while the user working on different machines did not feel any difference between them.

Since their release, the PC-DOS and MS-DOS operating systems have evolved in parallel and in similar ways. In 1982, versions 1.1 appeared. The main advantage of the new version was the ability to use double-sided floppy disks (version 1.0 only allowed working with single-sided floppy disks), as well as the ability to send printer output to other devices.

In 1983, versions 2.x were developed. Compared to the previous ones, they made it possible to use HDD(at that time, having a hard drive was not only optional, but also made the computer “super sophisticated”), provided a sophisticated hierarchical disk directory, included built-in devices for floppy disks and a file management system.

MS-DOS version 3.0, released in 1984, offered an improved option for servicing the hard drive and connected microcomputers; subsequent versions, including 3.3 (which appeared in 1987), developed in the same direction.

Returning to CP/M: this system also evolved, and in 1988 Digital Research turned CP/M into DR DOS...

MS-DOS version 5.0 (1991) provided the ability to use memory located above 1M, support for new 2.88 MB floppies was added, as well as several utilities, including UNDELETE - for restoring data deleted by mistake. In 1992, version 5.a appeared - it eliminated gross mistakes operation of the UNDELETE and CHKDSK utilities.

MS-DOS version 6.0, released in 1993, expanded the ability to use memory located above 1M, added the Memmaker memory optimization utility and the DoubleSpace tool for increasing effective disk space, as well as checking and hard optimization disk ScanDisk and Defrag and antivirus program(it should be noted that after legal proceedings with the Stack company regarding the copyright of DoubleSpace, the latter was replaced in MS DOS 6.22 with a similar utility DriveSpace).

In 1983, MS DOS was modernized several times - versions 6.2 and 6.21 were released (mainly improvements consisted of removing DoubleSpace from the OS and including DriveSpace, DISKCOPY and updated utility SCANDISK); next year another update is coming out - version 6.22 with the DriveSpace utility included in it.

The next milestone in the development of MS-DOS was 1995, the year the Windows 95 operating system was introduced. MS-DOS included in Windows 95 was designated version 7.0 and had such important improvements as support for long file names (all previous versions supported names up to eight characters plus three characters for extension).

Starting with version 7.0, MS-DOS is supplied only with Windows, thereby clearly indicating the end of its turbulent history. In MS-DOS version 7.1, distributed in part of Windows 95 Service Release 2, support for the FAT32 file system and large hard drives, but in Windows Me, although MS-DOS 8 was included, it turned out to be so hidden deep inside Windows that loading “pure” DOS was impossible (DOS programs can only be run in Windows window), and the configuration files сonfig.sys and autoexec.bat, although they were saved so as not to “confuse” old programs, when booting Windows stopped being processed.

On the other hand, even in Windows Me MS-DOS is not a simple “add-on”, but represents one of the required components of the system: if, for example, you replace the IO.SYS file with a similar one, but from one of previous versions Windows, we will receive a message that MS-DOS 8 is required to boot the system. However, the role of MS-DOS in Windows Me has become minimal - the same IO.SYS transfers control directly to VMM32.VXD, that is, to the Windows kernel...