DISK OPERATING
SYSTEM (DOS)
Operating System
Definition:
Sometimes abbreviated as "OS“, an
operating system is the program that,
after being initially loaded into the
computer by a boot program, manages all
the other programs in a computer.
The other programs are called
applications or application programs.
Operating System
Definition (continuation):
The application programs make use of
the operating system by making requests
for services through a defined
application program interface (API).
In addition, users can interact directly
with the operating system through a user
interface such as a command language
or a graphical user interface (GUI).
Operating System
Functions:
1. Allocating and assigning system
resources
2. Scheduling operations
3. Monitoring system activities
4. Standard means of communication
between user and computer
Operating System
Examples of Operating Systems:
1. DOS - Disk Operating System
− one of the first operating systems
for the personal computer. When
you turned the computer on all you
saw was the command prompt
which looked like c:\ >. You had to
type all commands at the command
prompt which might look like
c:\>wp\wp.exe. This is called a
command-line interface.
Operating System
Examples of Operating Systems:
2. Windows
− A product of Microsoft, it is a GUI
(graphical user interface)
operating system. This type of "user
friendly" operating system is said to
have WIMP features:
Windows
Icons
Menus
Pointing device (mouse)
Operating System
Examples of Operating Systems:
3. MacOS - Macintosh
− a product of Apple, has its own
operating system with a GUI and
WIMP features.
4. Unix - Linux (the PC version of
Unix)
− Unix and Linux were originally
created with a command-line
interface, but recently have added
GUI enhancements.
Disk Operating System
 It was the first widely-installed
operating system for personal
computers.
Earlier, the same name had been used
for an IBM operating system for a line
of business computers.
 The first personal computer version of
DOS, called PC-DOS, was developed
for IBM by Bill Gates and his new
Microsoft Corporation.
He retained the rights to market a
Microsoft version, called MS-DOS.
Disk Operating System
 PC-DOS and MS-DOS are almost
identical and most users have referred
to either of them as just "DOS.“
 DOS was (and still is) a non-graphical
line-oriented command- or menudriven operating system, with a
relatively simple interface but not
overly "friendly" user interface.
 Its prompt to enter a command looks
like this:
C:>
Disk Operating System
DOS Prompt
− The message DOS displays when it is
ready to accept input on the command
line.
The default DOS prompt (C:\>, D:\>,
etc.) displays the current drive and
directory.
Disk Operating System
Types of DOS Commands:
1. Internal Commands
These commands do not require any
special files for being executed and
are brought into the computer's
memory as soon as the computer is
switched on.
Examples:
COPY, DEL, DIR, TYPE, CD, MD,
CLS, DATE, TIME and PATH.
Disk Operating System
Types of DOS Commands:
2. External Commands
These commands require certain
special DOS files to get executed.
Examples:
FORMAT, CHKDSK, XCOPY, PRINT,
ATIRIB, DISKCOPY, etc.
Disk Operating System
Basic DOS Commands:
1. CLS (internal)
− Clears the screen.
2. DATE (internal)
− View or change the systems date.
3. TIME (internal)
− View or modify the system time.
4. VER (internal)
− Displays the version information.
Disk Operating System
Basic DOS Commands:
5. DIR (internal)
− List the contents of one or more
directory.
Disk Operating System
File Name
− The name of a file.
Example:
EXER1.DOC
File Name
Base Name Extension
(8 char)
(3 char)
Disk Operating System
Considerations in giving a file a
name:
1. A file name can contain a number but
it cannot start with a number.
2. A file name cannot contain white
spaces; the underscore can be used
instead to separate characters.
3. Give a file a name that would tell you
about the contents of the file.
Disk Operating System
File Manipulation Commands:
1. COPY (internal)
− Copy one or more files to an
alternate location.
Format:
COPY <source> <destination>
2. RENAME/REN (internal)
− Renames a file or directory.
Format:
RENAME <old name> <new name>
Disk Operating System
File Manipulation Commands:
3. DEL (internal)
− Deletes one or more files.
Format:
DEL <file name>
4. TYPE (internal)
− Display the contents of a file.
Format:
TYPE <file name>
Disk Operating System
Directory Commands:
1. MD/MKDIR (internal)
− Command to create a new
directory.
Format:
MD <directory name>
2. CD/CHDIR (internal)
− Changes directories.
Format:
CD <directory name>
Disk Operating System
Directory Commands:
1. RD/RMDIR(internal)
− Removes an empty directory.
Format:
RD <directory name>
Conditions to be satisfied before a
directory can be removed:
1. The directory to be removed must be
empty.
2. The directory to be removed must not
be the current directory.
Directory Tree
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