MS-DOS

MS-DOS (stands for Microsoft Disk Operating System) was the member more popularly known family of operating systems DOS from Microsoft, and the main system for personal computers Compatible with IBM PC in the 1980s and mid 90s, until it was gradually replaced by operating systems that offered a graphical user interface, in particular by several generations of Microsoft Windows. This was one of the first operating systems for personal computers.

MS-DOS was born in 1980. When tasked with Microsoft to produce an operating system for personal computers range of IBM PC of IBM. At this time, Microsoft bought the rights to QDOS, also known as 86-DOS, of Seattle Computer Products that was developed by Tim Paterson, and began working on the modifications to meet IBM's requirements.

History

When IBM developed its IBM PC, they initially had their own operating system in mind. The BASIC - interpreter would by Microsoft of Bill Gates delivered.

However, when the company's own operating system did not run smoothly, IBM turned to Microsoft. A deal was concluded that Microsoft would write an operating system. Bill Gates decided not to start it himself, but went looking for a suitable product at other companies.

The operating system he found was QDOS (a Quick and Dirty Operating System derived from CP/M, hence the 'D'), which Microsoft bought for the sum of $50,000 and then further developed it himself. Microsoft adapted the system according to the wishes of IBM, that it sold under the name PC-DOS.

However, the contract with IBM stated that Microsoft could also sell DOS independently to third parties. Microsoft did this under the name MS-DOS. When PC clones appeared on the market in addition to the IBM PC, MS-DOS quickly became popular and Microsoft began its advance in the computer world.

MS-DOS was developed from QDOS, Quick and Dirty Operating System, also known as 86-DOS. Its development officially began in 1981 and was launched in 1982 as MS-DOS 1.0. It had nine major versions and reached wide dissemination, but was gradually replaced by operating systems that offered a graphical user interface (GUI), in particular, by several generations of the Microsoft Windows operating system.

Versions

• PC DOS 1.0 was the first version - Released in 1981 as a complement to the IBM-PC. First version of DOS. Supports 16 KB of RAM, 5.25-inch single-sided 160 KB disks. 22 orders It allows files with extension .com and .exe. It incorporates the command interpreter COMMAND.COM.
• PC DOS 1.1 - Fixed many errors, supports 5.25 double density floppy disks - First version released with the name MS-DOS.
• MS-DOS 2.0 - IBM XT plug-in released in 1985. More than double new orders support hard disk (about 5 MB).
• PC DOS 2.1 - Supplement to the IBM PCjr. Added some improvements.
• MS-DOS 2.11 - Added support for other languages and LAN support.
• MS-DOS 3.2 - Added capacity for 3.5-inch and 720 KB floppy disks.
• PC DOS 3.3 - Added support for computer PS/2 of IBM and the new 3.5 inch diskettes high capacity (1.44 MB). New international character code pages added, with support for 17 countries.
• MS-DOS 3.3 - Ability to create disk partitions larger than 32 MB. Support 4 serial ports (before only 2). Incorporation of the "Files" order to open up to 255 files simultaneously.
• MS-DOS 4.0 - Generated with IBM source code not with Microsoft.
• PC DOS 4.0 - Added DOS Shell, some improvements and fixes.
• MS-DOS 4.01 - Version to correct some error.
• MS-DOS 5.0 - Implemented in 1991, including more memory management features and tools for macro support, improved command interpreter or shell.
• MS-DOS 6.0 - Released in 1993, includes support for Microsoft Windows, utilities such as Defrag (disk defragmentation), DoubleSpace (file compression), MSBackup (backup copies), MSAV (Microsoft Anti-Virus), MemMaker, etc.
• MS-DOS 6.2 - Version to correct errors.
• MS-DOS 6.21 - DoubleSpace disk compression support removed.
• PC DOS 6.3 - Released in April 1995.
• MS-DOS 6.22 - Latest version distributed separately. DriveSpace included to replace DoubleSpace.
• PC DOS 7.0 - Add Stacker to replace DoubleSpace.
• MS-DOS 7.0 - Distributed together with Windows 95. Includes support for long file names (until now they had had the 8 + 3 restriction).
• MS-DOS 7.1 - Integrated in Windows 95 OSR2 and later in Windows 98 and 98 SE. Supports FAT32 file systems.
• MS-DOS 8.0 - Integrated in Windows ME. Although initially there was no separation between the two operating systems, later updates allowed.

Latest version

The development of MS-DOS as an independent operating system has been discontinued. The last standalone version was 6.22. From version 7.0, MS-DOS is no longer a separate operating system, but directly integrated into Windows. MS-DOS was still fairly visible in Windows 95 and 98, but in Windows Me most traces were erased. A Chinese MS-DOS fan (Wengier) has made an independent version of the most extensive version. This is MS-DOS 7.1, introduced by Microsoft with Windows 95 OSR2, this was for everyone to download for free, but at the moment this is no longer possible.

MS-DOS in Windows

Windows 95, Windows 98 and Windows Me as well as the versions for that use MS-DOS to start, after which the graphic shell takes over. MS-DOS is not a multitasking operating system, which means that only one program can work at a time. By using virtual processors (in practice the V86 mode of the 80386 processor and higher), however, it is possible to run different MS-DOS programs each in their own virtual computer. However, this method can be problematic because many MS-DOS programs want to directly control the hardware. An advanced operating system can allow this, but at the expense of stability (setting the hardware incorrectly can cause the computer to crash), or virtualizing the hardware, whereby the operating system monitors what the MS-DOS program has with the hardware is doing.

The Windows 3.x and 9x operating systems allow direct communication with the hardware, unless a driver (operating program) virtualises it. The Windows NT operating systems do not allow this, there must always be a driver that makes the hardware accessible to an MS-DOS program. However, the Windows NT operating systems cannot influence the way in which the third-party drivers use the hardware. OS/2 uses the same philosophy as Windows NT, but the user can set individual programs to allow them to directly control the hardware.

Source Code

In 2014, Microsoft published the source code for MS-DOS 1.1 and 2.0 in collaboration with the Computer History Museum. The source code of the MS-DOS 1.1 (1982) and 2.0 (1983), together with that of Word for Windows 1.1a (1989) was published by Microsoft on March 25, 2014. It is available in the following GitHub repository: https://github.com/microsoft/ms-dos

Features

In version 2.0, launched in 1983, Unix's own features were introduced, such as the use of subdirectories, pipelines, redirection of incoming and outgoing orders, as well as support for hard drives and floppy disk drives of 360 KiB capacity.

Basic Orders

Here are some of the commands used by MS-DOS, which can currently be used from the command line in Windows operating systems. To access the help of these, MS-DOS, from version 6.2 allows the following: command_to_consultation /? (Ex.: copy /?). They can be internal (included within COMMAND.COM itself) or external (executable files in the MSDOS directory).

Internal Commands

Internal or resident commands are those that are transferred to memory at the time of loading the Operating System and can be executed without having the DOS present in the default unit from which the command can be executed. The default unit is the unit it is in, for example A:\>_; and the specified unit is the one to which we address or specify being in another unit, for example A:\> B:, the specified unit is B.

• CD or CHDIR - Change the current directory.
• CD .. - Change to the hierarchically superior directory.
• CLS - Cleans all commands and all information on the screen except the command prompt, usually the letter and path of the unit used (For example C:\>)
• COPY - Copy a file from one directory to another
• COPY CON - Copy the characters entered on the screen to a file
• DATE - View or change the system date.
• DEL - Used to delete files.
• DIR - List the directories and files of the current drive or directory.
• FOR - Repeat a command
• PROMPT - Change the order display line.
• MD or MKDIR - Create a directory
• RD or RMDIR - Delete a directory.
• REM - Allows you to insert comments in batch files.
• REN or RENAME - Rename files and directories.
• SET - Assigns values to environment variables.
• TIME - Displays or changes the system time.
• TYPE - Shows the contents of a file. It is mainly used to view file contents in text format.
• SEE - Shows the version of the Operating System.
• VOL - Shows the hard disk label and its volume (if it has one).
• BREAK - Activate or deactivate the extended verification CTRL + C.
• EXIT - Exit.

External Commands

External commands as opposed to internal commands are stored in script files called transient or external, and to execute they need these files, in addition external commands have their own name and can be copied from one disk to another.

Here are some of the commands that MS-DOS used, and that can currently be used from the command line in Windows operating systems. To access the help of these, MS-DOS, from version 6.2 allows the following: command_to_consultation /? (Ex.: copy /?). They can be internal (included within COMMAND.COM itself) or external (executable files in the MSDOS directory):

• ATTRIB - Without parameters it displays the attributes of the directories and files. With parameters, change the attributes of directories and files.

The attributes of the directories and the files are: read (r), write (w), file (a), hidden (h), system (s). Parameters: signs (more or less) and letters r, w, a, and h "v". Example: Attrib + r *.* (Read-only attribute, for all files in that directory).

• APPEND - Used to specify paths for data files.
• BACKUP - Run a backup of one or more files from a hard disk to a floppy disk.
• CHKDSK - Check for errors on the hard disk. (It can also be used to correct them with the "/F" parameter).
• DELTREE - Deletes a directory regardless of whether it contains subdirectories with all its contents.
• DISKCOMP - After making a copy of diskettes we can perform a verification, to see if you have copied all the contents, comparing. This command compares disks or diskettes.
• DISKCOPY - Allows you to make an identical copy from one floppy disk to another, belongs to the group of external orders.
• DOSKEY - It allows to keep residents in RAM memory the orders that have been executed in the indicative point.
• FC - Compare files.
• FORMAT - Allows you to create the logical structure in a physical storage unit (hard drives, floppy disks and mass storage units).
• FORMAT / U - Formats an unconditionally formatted disk repairing errors and marking bad sectors.
• FORMAT / s - Formats a disk and converts it into a system disk.
• PRINT - Allows you to print files.

You can use these combined parameters.

• KEYB - Sets the keyboard language according to the added parameter (Example: KEYB SP for the Spanish keyboard).
• LABEL - Displays or changes the label of the hard drive.
• MEM - Shows RAM, occupied space and free space.
• MOVE - Move or change a directory and / or files. It also renames subdirectories.
• SUBST - Creates a virtual logical drive from a directory.
• TREE - Shows tree-shaped directories.
• XCOPY - This command has the same function as its resident counterpart COPY, with the proviso that it performs copy operations of the entire directory structure if the wildcard character *.* and the /s switch are used. It is an improved version of the previous one.

Redirects

• < - Re-routing of the standard input. Its syntax is command < file.
• > - Re-routing of the standard output. Its syntax is command > file. If the file does not exist, create it. If it already existed, overwrite its content.
• >> - Re-routing of the standard output to an existing file. Its syntax is command >> file. If the file does not exist, create it. If it already existed, add the result of the command following the previous content of the file.