ABOUT DOS
• DOS was a single-user and single-tasking operating system, which meant that only one program could be run at a time by a single user.
• Microsoft DOS (Disk Operating System) is a command line user
interface (means - there was no mouse, no menus, or any graphical
components).
• MS-DOS 1.0 was released in 1981 for IBM computers and the
latest version of MS-DOS is MS-DOS 6.22 released in 1994.
• While MS-DOS is not commonly used by itself today, it still can
be accessed from Windows 95, Windows 98, Windows ME,
Windows 2000, Windows XP, Windows Vistas or Windows 7 by
clicking Start / Run and typing command or CMD in Windows
NT, 2000 or XP.
PURPOSE OF DOS
• DOS has hidden power, because with DOS we can interact more
directly with the components of the computer than we can with
more modern operating systems. It is this power that makes it
valuable to know DOS today.
• The majority of computer users today use graphical systems, but
users of Windows, for instance, have the ability to interact with the
computer through DOS (or in the case of NT, with a DOSanalogue)
to do things, which are difficult or impossible to accomplish through the graphical interface.
• Familiarity with DOS is still considered essential for anyone
supporting Intel-based machines running Windows.
File system
DOS uses a filesystem which supports 8.3 filenames; 8 characters for the filename and 3 characters for the extension. Starting with DOS 2 hierarchical directories are supported.
Each directory name is also 8.3 format but the maximum directory path length is 64 characters due to the internal current directory structure (CDS) tables that DOS maintains.
Including the drive name, the maximum length of a fully qualified filename that DOS supports is 80 characters using the format drive:\path\filename.ext followed by a null byte.
Including the drive name, the maximum length of a fully qualified filename that DOS supports is 80 characters using the format drive:\path\filename.ext followed by a null byte.
MS-DOS Commands
Commands can be categorized into INTERNAL (memory resident) and EXTERNAL (utilities / programs) types.
INTERNAL COMMANDS :
• Internal commands are embedded into the command.com file.
• Internal commands are memory resident commands. They are
resident in the memory when the COMMAND.COM is loaded in
the boot up process.
• COMMAND.COM is a command processor, which works as an
interface between the user and DOS. It basically interprets what
user has typed at the DOS prompt and processes them.
1. BREAK Sets or clears extended CTRL+C checking.
2. CD Displays the name of or changes the current directory.
3. CLS Clears the screen.
4. COPY Copies one or more files to another location.
5. DATE Displays or sets the date.
6. DEL Deletes one or more files.
7. DIR Displays a list of files and subdirectories in a directory.
8. EXIT Quits the COMMAND.COM program (command interpreter).
9. MD Creates a directory.
10. PATH Displays or sets a search path for executable files.
11. PAUSE Suspends processing of a batch file and displays a message.
12. PROMPT Changes the MS-DOS command prompt.
13. REM Records comments (remarks) in a batch file or config.sys.
14. REN Renames a file or files.
15. RD Removes a directory.
16. TIME Displays or sets the system time.
17. TYPE Displays the contents of a text file.
18. VER Displays the MS-DOS version.
19. VOL Displays a disk volume label and serial number.
EXTERNAL COMMANDS
• External commands are MS-DOS utilities / programs. These are
the .EXE or .COM programs located on our hard drive.
• External commands are not embedded into the command.com and
therefore require separate files to be used.
• They are normally placed under C:\DOS, the default directory.
MS-DOS will load external commands if and only if user instructs
to execute them at the DOS prompt and /or in a batch program.
THE COMMANDS ARE -
1. APPEND Allows programs to open data files in specified directories as if they were in the current directory.
2. ATTRIB Displays or changes file attributes.
3. CHKDSK Checks a disk and displays a status report.
4. COMMAND Starts a new instance of the MS-DOS command
interpreter.
5. COMP Compares the contents of two files or sets of files.
6. DEBUG Starts Debug, a program testing and editing tool.
7. DELTREE Deletes a directory and all the files and subdirectories in it.
8. DISKCOMP Compares the contents of two floppy disks.
9. DISKCOPY Copies the contents of one floppy disk to another.
10. DOSKEY Edits command lines, recalls MS-DOS commands, and creates macros.
11. DOSSHELL Starts MS-DOS Shell.
12. EDIT Starts MS-DOS Editor, which creates and changes ASCII files.
13. EXPAND Decompresses one or more compressed files.
14. FASTHELP Provides summary Help information for MS-DOS
commands.
15. FASTOPEN Decreases the amount of time needed to open frequently used files and directories.
16. FC Compares two files or sets of files, and displays the differences between them.
17. FDISK Configures a hard disk for use with MS-DOS.
18. FIND Searches for a text string in a file or files.
19. FORMAT Formats a disk for use with MS-DOS.
20. GRAPHICS Loads a program that can print graphics.
21. HELP Provides complete, interactive Help information for MS-DOS commands.
22. LABEL Creates, changes, or deletes the volume label of a disk.
23. MEM Displays the amount of used and free memory in your system.
24. MODE Configures a system device.
25. MORE Displays output one screen at a time.
26. MOVE Moves one or more files. Also renames files and directories.
27. MSAV Scans your computer for known viruses.
28. MSBACKUP Backs up or restores one or more files from one disk to another.
29. MSD Provides detailed technical information about your computer.
30. POWER Turns power management on and off.
31. PRINT Prints a text file while you are using other MS-DOS
commands.
32. QBASIC Starts the MS-DOS QBasic programming environment.
33. REPLACE Replaces files.
34. RESTORE Restores files that were backed up by using the BACKUP command.
35. SCANDISK Checks a drive for errors and repairs any problems it finds.
36. SETVER Sets the version number that MS-DOS reports to a program.
37. SHARE Installs file-sharing and locking capabilities on your hard disk.
38. SORT Sorts input.
39. SYS Copies MS-DOS system files and command interpreter to a disk specified.
40. TREE Graphically displays the directory structure of a drive or path.
41. UNDELETE Restores files previously deleted with the DEL command.
42. UNFORMAT Restores a disk erased by the FORMAT command.
43. VSAFE Continuously monitors your computer for viruses.
44. XCOPY Copies files (except hidden and system files) and directory
trees.
Advantages:
Disadvantages:
Advantages:
- 1. Will run on a much smaller system. (ENTIRE OS can be placed on a SINGLE MODERN ROM chip!)
- 2. Gives more "direct" control of the processes.
- 3. Because of smaller size will "boot" much faster than ANY windows version.
- 4. Is easier to write "special purpose" programs for, so long as they don't require "fancy" graphics.
- 5. Allows to make use of the "old, slow" system hid in the closet when you bought the "new" one.
Disadvantages:
- 1. Very few "new" programs available, therefore need to be able to write programs in many cases.
- 2. Not nearly as fancy in the graphics department.
- 3. Not compatible with current "browsers" and most internet.
