Introduction to MS-DOS

Ms-Dos stands stands for Microsoft Disk Operating System. Ms- DOS is an operating system. An operating system is collection of system programs, used for controlling input/output operation. It is also known as interface between hardware and user. A operating system may be considered as the language translator  which converts the users readable codes into machine readable codes, means machine level language or binary digits. 

When we start MS-DOS, we get a symbol on the screen like this

C:\>

This symbol is known as C drive or C-prompt. similarly A:\> is called A-prompt or A drive. Generally A:\ is used as floppy drive i.e. when we are working on floppy disk and C:\ is used for local disk or hard disk. A small blinking bar we see on the screen. This is cursor. It is waiting for your instruction. There few predefined words for DOS. These are known as DOS-Commands. Our operating system can understand only these predefined commands.

These DOS-Commands are divided into two parts.

Internal Commands

External Commands

Before we go on detail in these commands, let first we understand a term called File and Directory. A file may be known as container of information on a particular topic. A directory may be considered as a structure or a cabinet which keeps one or more files. Directories are usually creates for keeping one or more identical files together.  Every file have a filename which helps to recognize them. these are divided into two parts

File name or Primary name

Extension or Secondary name

The primary name can be from 1 to 8 characters long. The extension contains 1 to 3 characters long. A filename and extension are separated by using a dot symbol. Thus it's structure looks like

Filename        .        Extension

Primary name .        Secondary Name  

The valid characters for giving a file name are form A to Z and the digits are form 0 to 9. Special symbols are ~ ^ % # @ ! _ - { } [ ] ' `.

Extensions or secondary names are usually used for denoting the type of files or the type of informations stored in the file. Like the filename have extension EXE, BAT, COM are respectively Executable, Batch and Command files, which are given high priority by DOS. Because these files could be directly understand by operating system. Similarly the filename having extension BMP, GIF, JPEG etc. are the extension for graphical files. The files having extension C or CPP are the files of C/C++ language, BAS for BASIC language, PAS for PASCAL programming and so on.