The Development of MS-DOS

Introduction to the operating system

DOS, as with any operating system, controls computer activity. It manages operations such as data flow, display, data entry amongst other various elements that make up a system.

The role of DOS is to interpret commands that the user enters via the keyboard. 
These commands allow the following tasks to be executed:

• file and folder management
• disk upgrades
• hardware configuration
• memory optimisation
• program execution

These commands are typed after the prompt, in the case of MS-DOS (Microsoft DOS, the most well known): the drive letter followed by a backslash, for example: A:\ or C:\. 
 
To execute a command type the command then hit ENTER.

Files in MS DOS

In a computers data is stored in files. When you run a program, MS-DOS processes the data stored in the file and passes it to the system. 
In MS-DOS a file can be any size, however the file name is more restricted, it can only have a maximum length of 8 characters plus 3 for the extension.

Furthermore, the files can only contain the following characters:

• letters A to Z
• numbers 0 to 9
• the following special characters: $~! # % & - { } ( ) @ ' _ ^

Thus filenames must not contain:

• spaces
• commas
• backslash
• dot (apart from the dot that separates the name and the extension)

nor can they contain any of the following list of reserved names:

• CLOCK$
• CON
• AUX
• COM1
• COM2
• COM3
• COM4
• LPT1
• LPT2
• LPT3
• NUL
• PRN

Organising files in directories or folders

Depending on its size a hard drive may contain several thousands of files. However, the more files there are, the more difficult it is to manage them, this is when we need to store them in directories In MS-DOS, directory names are also subject to the same name restrictions as files (8 characters for the name, and an extension with 3 characters).

Installing MS-DOS

When installing MS-DOS, make sure that in the BIOS the the boot disk is set to A: first, then the hard drive (boot sequence: A:, C:) Then insert disk 1 in the A: drive, power up the computer, then follow the on-screen instructions. 
You must enter the following information:

• time and date
• country
• the media on which to install the operating system (make sure the drive is accessible and has sufficient free disk space)
• the storage folder for MS-DOS files
• if the MS-DOS shell should appear on each start-up
• if MS-DOS should occupy a single partition taking up the entire hard drive

Creating a system boot disk

After MS-DOS has been installed you should create a system boot disk. 
Once you have inserted a blank floppy disk into the drive enter the following command:

format a: /s

The /s switch means "copy system files".

This floppy disk can be used to boot the system by inserting it in the floppy disk drive and restarting the computer.

Summary

Command	Description
dir	lists the contents of a folder
cd	changes folder
cd ..	parent folder
md or mkdir	creates a new folder
deltree	deletes a folder and all sub-folders
copy, xcopy	copies a file
move	moves a file
del	deletes a file
type	displays the contents of a file
type |more	displays file contents page by page, pausing after each page
help	help for the given command
print	prints the given file
attrib (-/+r, -/+a, -/+s, -/+h)	changes a file's attributes (- deactivates, + activates, r: read-only, a: archive, s: systeme, h: hidden file)
format	formats the given drive
label	assigns a drive name to a drive
ver	gives the version number