Ms dos

In 1981, IBM placed a request for an operating system to be used in the new IBM PC family of computers. Microsoft bought the rights to the 86-DOS operating system from Seattle Computer Products ^[3] and began work on its modification to the requirements of IBM. Subsequently, IBM licensed MS-DOS and released it in August 1981 under the name PC DOS 1.0. Subsequently, the development of MS-DOS and PC DOS was conducted by Microsoft and IBM jointly until 1993, when two separate releases were released - 6.0 from Microsoft and 6.1 from IBM.

During the existence of MS-DOS, eight major releases (1.00, 2.00, etc.) and two dozen intermediate releases (3.10, 3.30, etc.) were released, until in 2000 Microsoft stopped its development. Initially, MS-DOS focused on the Intel 8088 processor used in the first IBM PC , and worked only with floppy disks on which the OS itself, as well as programs and user data, were located. Subsequent versions acquired the ability to work with various types of drives, such as a hard disk and CD-ROM , added support for new processors and computer architectures. This was a key product of the company, which provided it with substantial income and a marketing resource. During the development of Microsoft, it turned from a developer of a programming language into a large company producing a wide variety of software. MS-DOS also became the base layer for early versions of Windows , running as a graphical user interface on top of the command line.

The latest boxed version was 6.22, but MS-DOS continued to serve as a bootloader for Windows 95 (versions 7.0 and 7.1), Windows 98 (version 7.1), and Windows ME (version 8.0).

On March 25, 2014, the Mountain History Museum of Computer History, with permission from Microsoft, unveiled the source code for the MS-DOS operating system (versions 1.1 and 2.0), released in 1981, as well as the Word text editor (1.1a) for Windows ^[4] . In 2018, the source code of the MS-DOS OS versions 1.25 and 2.0 was published under the free MIT license ^{[5] [6]} .

MS-DOS is a renamed version of 86-DOS ^[7] written by Tim Paterson of Seattle Computer Products ^[7] . Development of 86-DOS took only six weeks and was a Digital Research CP / M clone, ported for use on an 8086 processor and containing only two differences from the original: improved disk sector buffering logic and the new FAT12 file system. The first version of 86-DOS was released in August 1980 ^[8] . According to an agreement signed in November 1980 with IBM , Microsoft was required to provide an operating system for a new IBM PC based on Intel 8086 . To this end, Microsoft in May 1981 hired Tim Paterson to complete the adaptation of 86-DOS to the prototype IBM PC, and then in July of that year completely bought the rights to 86-DOS 1.10 for $ 75 thousand ^[7] . Microsoft kept the version numbering, but renamed the OS to MS-DOS. In August 1981, licensed by IBM, MS-DOS 1.10 / 1.14, under the name PC DOS 1.0, began shipping with new IBM PCs ^[8] .

In version 2.0, timed to coincide with the release of IBM PC XT with a hard drive, MS-DOS dramatically expanded the functionality of the OS, partially adapting the missing from Unix (for example, subdirectories, working with files through descriptors, redirecting input / output, accessing devices by name, and so on) like that). The scale of the changes is emphasized by the fact that most of the latest programs, including the latest versions of MS-DOS, have the line “DOS 2.0 or higher” in the requirements.

Initially, MS-DOS was developed as an operating system capable of running on any computer with an 8086 processor. Microsoft repeated the CP / M distribution model when each computer with different hardware used its own version of MS-DOS. For this, the OS had a modular structure with a minimum set of drivers for disk drives and a console integrated into the kernel, and installed drivers for other devices that were loaded and available at boot time. OEMs used the development kit provided by Microsoft to create their own version of MS-DOS with a standard kernel, but with I / O device drivers specific to their hardware. Manufacturers such a version is usually delivered on floppy disks with computers. Thus, there were many versions of MS-DOS for various hardware platforms, and IBM PC-compatible and MS-DOS-compatible computers should be distinguished. Some computers, such as Tandy 2000 , could run software written only for MS-DOS, but not software that utilized the features of the IBM PC architecture.

The design of the operating system implies good compatibility if the programs use only standard MS-DOS calls for their work. A similar philosophy was later implemented in Windows NT (see Hardware Abstraction Layer ). Nevertheless, in MS-DOS, the high speed of programs is achieved only through direct access to hardware, which was especially typical for games of that time, requiring significant computer resources. The dominance of the IBM PC-compatible architecture has led to the proliferation of numerous clones, and the need for separate hardware-dependent versions of the operating system has disappeared.

Subsequently, the dependence on IBM architecture caused a number of serious problems in the industry when changing the original design of the IBM PC. So, initially it was not intended to use more than 640 KB of RAM ( 640 KB barrier ), since higher areas of RAM were reserved for peripherals and ROMs. Manufacturers had to invent various schemes to bypass this obstacle ( EMS , XMS , etc.) to access additional memory. If the original idea of ​​independence from hardware was continued, then a similar problem could have been avoided. Thus, MS-DOS is an operating system operating in real mode of the processor with the x86 architecture, in which it can address no more than 1 MB of RAM.

For computers manufactured by IBM, a version called PC DOS was installed. For third-party manufacturers, Microsoft offered a version of DOS already under the name MS-DOS. Thanks to the collaboration between IBM and Microsoft, up to version 5.0, PC DOS and MS-DOS systems were practically the same. The first boxed version of MS-DOS was 5.0 in the Upgrade version, before which all releases were distributed only as an OEM product by personal computer manufacturers .

Version History

Minimum MS-DOS Fileset:

• kernel files:
  • IO.SYS - BIOS extension;
  • MSDOS.SYS - interrupt handling;

• command processor:
  • COMMAND.COM - command line interface support.

Strictly speaking, the presence of the COMMAND.COM file is not necessary to run MS-DOS. It can be replaced by another shell capable of executing the necessary commands. At one time, many third-party processors were released by third-party developers. The most common third-party command processor was NDOS.COM (licensed 4DOS ) from Symantec's Norton Utilities package.

In addition to the specified files, the SYS.COM and FORMAT.COM commands with the / S switch, starting with version 6.0, additionally transfer the DBLSPACE.BIN (6.0-6.2) or DRVSPACE.BIN (6.22) files responsible for working with compressed disks to the system disk Microsoft DoubleSpace or DriveSpace respectively.

Configuration files

To set the OS configuration, configuration files of a special format are used:

• CONFIG.SYS - configuring the system and loading device drivers during the initialization phase of MSDOS.SYS
• AUTOEXEC.BAT - start batch file . It is executed when the shell starts up at boot time.

The distribution also includes the following drivers and programs:

• ANSI.SYS is an advanced console driver (screen and keyboard).
• COUNTRY.SYS - file with localization tables, sorting alphabets.
• DISPLAY.SYS - display driver; in particular, it loads localized fonts.
• DBLSPACE.EXE - Microsoft DoubleSpace, disk compressor (6.0 - 6.2).
• DEFRAG.EXE - Microsoft Defragmenter, Disk Defragmenter.
• DOSSHELL.EXE - MS - DOS Shell , a shell using the two-pane principle with a pseudographic interface. In MS-DOS 6.2, it was ported to the optional MS-DOS Resource Kit.
• DRVSPACE.EXE - Microsoft DriveSpace, disk compressor (6.22).
• HIMEM.SYS - driver for additional (extended) and HMA memory.
• HELP.COM - online reference MS-DOS Help.
• EMM386.EXE - driver for expanded memory emulation and upper memory management ( UMB ).
• INTERLNK.EXE , INTERSVR.EXE - Interlnk inter -computer communications subsystem.
• KEYB.COM - a driver for switching language keyboard layouts.
• KEYBOARD.SYS - file with descriptions of language keyboard layouts, designed as a driver.
• * .CPI - downloadable fonts for screen and keyboard code pages.
• MEMMAKER.EXE - Microsoft MemMaker, upper memory optimizer.
• MODE.COM - a program for configuring a number of screen parameters and system I / O ports: serial , parallel .
• MSAV.EXE - Microsoft Anti-Virus for MS-DOS, antivirus.
• MSD.EXE - Microsoft Diagnostics, an information utility that displays PC configuration.
• MSBACKUP.EXE - Microsoft Backup for MS-DOS, backup and restore information.
• MWAV.EXE - Microsoft Anti-Virus for Windows, antivirus.
• MWBACKUP.EXE - Microsoft Backup for Windows, backup and restore information.
• MWUNDEL.EXE - Microsoft Undelete for Windows, recover deleted files.
• POWER.EXE is a power management driver.
• RAMDRIVE.SYS - electronic disk driver.
• SCANDISK.EXE - Microsoft Scandisk, a disk scanner-corrector.
• SMARTDRV.EXE - Microsoft SmartDrive, a disk caching program.
• VSAFE.COM - VSafe, a resident virus filter.
• UNDELETE.EXE - Microsoft Undelete for MS-DOS, recover deleted files.

Multitasking

• DESQVIEW
• DV / X

Network Clients and Servers

• Lantastic
• Personal netware

Computer to Computer Connections

• Laplink
• Norton link

Memory expansion

In connection with the development of the IBM PC / XT architecture , there was expanded , and then AT , additional memory that could be used in OS components and programs using the EMS, XMS, HMA , UMA / UMB mechanisms provided by the extended memory BIOS and DOS drivers - Microsoft memory managers (HIMEM and EMM386) or third-party managers (for example, QEMM ).

Shell

For MS-DOS, which provides the user with just a command line interface, a number of so-called shells have been created, that is, programs that allow you to make working with files more visual and convenient. The most famous of them:

• Norton Commander is the most popular commercial file manager in Russia. All file operations are performed on two panels using hot keys and, later, the mouse and menu. Recent versions include many plugins that greatly expand the functionality. In the image of Norton Commander, many file manager interfaces and other programs for various operating systems were later created.
• Volkov Commander is a clone of Norton Commander. Unlike Norton Commander, it supports long file names (for version 4.99 alpha). Very compact. The basic set includes only the file manager itself with a minimal but sufficient set of functions, and occupies about 64 Kbytes on the disk. Functionality is expanded by connecting other applications.
• DOS Navigator - further development of the idea of ​​Norton Commander. More functionality. More panels. Support for SVGA text modes (132 × 25 - 132 × 60). Multitasking window interface for plugins. Expansion due to easy and convenient connection of plug-ins and third-party applications.

Application developers for MS-DOS often used undocumented features and functions, as well as direct access to hardware to bypass the operating system. This is the reason that in Windows 9x and newer operating systems it is not always possible to run an application written for MS-DOS.

Another problem that users face when working with MS-DOS applications on modern computers is the significant difference in speed. In recent years, computer performance has increased significantly. Therefore, many games for MS-DOS on a modern computer are too fast, so the user does not have time to see what is happening on the screen and analyze the game situation. The reason for this is the use of loops to form delays. Modern processors execute them too quickly, and often even ignore them (the work of an intelligent optimizer). For the same reason, some applications stop working, displaying a division by zero error.

To solve the above and a number of other problems of working with MS-DOS applications running Windows NT and Unix-like operating systems, special emulators are used. At the moment, the most famous of them is DOSBox , which allows you to configure individual startup parameters for each MS-DOS application: the speed of the emulated computer, the emulated sound and video card, etc. Sometimes processor slowdowns are used.

On April 1, 2015, Microsoft released the comic application MS-DOS Mobile for its Windows Phone 8 / 8.1 OS, which simulates the MS-DOS console interface. However, it is not a full-fledged system emulator and does not support most of the functions available in the original MS-DOS ^[23] .

• DOS Command List
• DOS Extender
• DOS for IBM PC-compatible computers

•   Wikimedia Commons has MS-DOS related media files
• GitHub MS-DOS Project - MS-DOS 1.25 and 2.0 Source Code
• The history of the emergence and development of the MS-DOS operating system, describes the changes in various versions
• KB71986 MS-DOS 5.0 Internal and External Commands
• MS-DOS Celebrates Thirty Years of Compulent , July 27, 2011