UNIT 1:

MS-DOS
MS-DOS (which stands for Microsoft Disc Operating Systems) is a Microsoft
developed OS. This came out initially in 1981 and quickly became the
preferred OS over IBM-compatible desktop computers in the decades that
followed.
Microsoft's DOS is an interface for the command line (CLI) OS, which means it
lacks the visual user interface (GUI) found in modern OSes like Microsoft
Windows or Mac OS. Clients communicate with the OS instead by entering
instructions into an administrative prompt
MS-DOS was intended to serve as a simple and efficient computer operating
system capable of running on cheap-powered hardware. It included basic
features like managing files, disc presentation, and disc services. Microsoft's
DOS transformed over the years to accommodate advanced functions such
as social media, handling memory, and performing multiple tasks.
The MS-DOS eventually got supplanted by Windows from Microsoft, which
included a graphical user interface and enhanced features. MS-DOS, on the
other hand, is a significant component of calculating the past and continues
to be utilized in specialized tasks and systems that are embedded

MS-DOS Architecture
The architecture of MS-DOS (Microsoft Disk
Operating System) includes the following
components

 Application Program ? Application programs refer to the software

applications that users interact with to perform specific tasks. These
programs could include word processors, spreadsheets, games, or any
other software designed to run on MS-DOS. Application programs are
written by software developers using programming languages
compatible with MS-DOS.
 Resident System Programs ? Resident system programs are
essential components of the operating system that remain in memory
throughout the computer's operation. These programs provide various
system services and utilities required for the functioning of MS-DOS.
Examples of resident system programs in MS-DOS include the
command interpreter (COMMAND.COM), which handles user commands
and runs programs, and the disk caching system, which improves disk
read/write performance.
 MS-DOS Device Drivers ? MS-DOS device drivers are software
modules that enable communication between the operating system
and specific hardware devices connected to the computer. These
drivers provide an interface for MS-DOS to access and control devices
 such as printers, keyboards, mice, disk drives, and display adapters.
Device drivers allow MS-DOS to manage the hardware resources
efficiently and provide a standardized way for applications to interact
with hardware devices.
 ROM BIOS Device Drivers ? ROM BIOS (Read-Only Memory Basic
Input/Output System) device drivers are low-level software modules
stored in the computer's firmware. These drivers provide the necessary
instructions for MS-DOS to communicate with hardware devices during
the boot process. ROM BIOS device drivers initialize hardware
components such as the keyboard, display, disk drives, and other
peripherals, enabling MS-DOS to interact with them from the moment
the computer starts up.

Advantages
 Efficient use of system resources ? MS-DOS was developed for use
on negligible-powered hardware, making it a perfect match for first-
generation desktop machines with little power for processing and
storage.
 Simple and intuitive command-line interface ? MS-DOS was
developed for use on negligible-powered hardware, making it a perfect
match for first generation desktop machines with little power for
processing and storage
 The wide availability of software ? Microsoft's DOS quickly
established itself as the dominant OS for desktop computers, spawning
a plethora of applications and programs for it.
 Compatibility with a wide range of hardware ? The MS-DOS may
have been utilized via an extensive variety of combinations of
hardware due to the fact that was developed to be appropriate with the
components of IBM compatible desktop machines.
 Stability ? The MS-DOS was an efficient and dependable OS that was
widespread in corporate and commercial conditions.

Disadvantages
Microsoft's DOS has multiple drawbacks over the various operating systems
at that point in time, which include the following ?
 Limited multitasking support ? Microsoft DOS served as a focusing-
on one- task computer operating system that was capable of running
 one program at a time. As a result, it was far less effective compared to
contemporary OSes, which allow for numerous programs concurrently.
 No graphical user interface(GUI) ? Microsoft's DOS lacked a
graphical user interface, making it a bit harder for users unfamiliar with
the command line interface to get acquainted with the OS.
 Lack of built-in networking support ? The MS-DOS lacks socializing
assistance, making it more challenging to communicate with machines
to exchange materials.
 Lack of plug-and-play support ? Microsoft's DOS wasn't compatible
with plug-and-play equipment, so individuals had to customize and
construct hardware devices manually.
 Vulnerabilities to security threats ? Microsoft's DOS was a prompt
operating system that didn't have numerous of the safety includes now
found in contemporary operating systems.
 To summarize, Microsoft's DOS proved to be a revolutionary OS that
aided in the establishment of personal the field of computing. While it
experienced many benefits, which included effective utilization of the
system's assets, a simple and intuitive control-line interface,
widespread software availability, connectivity with an extensive variety
of equipment, and equilibrium, it additionally came with several
drawbacks, including limited juggling of several tasks support, a lack of
a GUI, a lack of embedded collaboration support, a do not have of plug-
and-play encouragement, and weaknesses to security threats.
 Regardless of its shortcomings, the MS-DOS established the path for
the invention of contemporary operating systems and performed a
significant role in information technology over the course of time. It
continues to be employed in some specialized programs and
embedded machines today, and its history lives on in interfaces for the
command line as well as other contemporary Linux operating system
features.

Types of DOS Commands

 nternal Commands ? Internal commands are the commands that are
built into the command interpreter or the command prompt of the DOS
operating system. These commands do not require a separate
executable file to run and can be used directly from the command
prompt.
  External Commands ? External commands in DOS are commands
that are not built into the command interpreter, but are separate
executable files that need to be located in the system's path or
directory to be executed from the command prompt. External
commands are usually more complex and are used for more advanced
tasks than internal commands.

Internal DOS Commands

Internal or Basic DOS commands are simple and essential commands that
users can use to interact with the file system and execute simple tasks. Here
are some examples of basic DOS commands ?
 DIR ? Displays a list of files and directories in the current directory.
 CD ? Changes the current directory to a specified directory.
 MD ? Creates a new directory.
 RD ? Removes an empty directory.
 COPY ? Copies a file from one location to another.
 DEL ? Deletes a file.
 REN ? Renames a file or directory.
 TYPE ? Displays the contents of a text file.
 ECHO ? Displays messages or turns command echoing on or off.
 VER ? Displays the version number of the operating system.
 DATE ? Displays or sets the system date.
 TIME ? Displays or sets the system time.
 CLS ? Clears the screen.
 PROMPT ? Change the command prompt.
 TREE ? Displays a graphical representation of the directory structure.
 FC ? Compares two files or sets of files and displays the differences
between them.
 FIND ? Searches for a specific string of text in a file or files.
 FINDSTR ? Searches for a specific string of text in a file or files, with
advanced search options.
 PATH ? Displays or sets the system's path variable, which tells the
system where to look for executable files.
 SET ? Displays or sets the values of environment variables, which are
used by the system and other programs.
 SHIFT ? Changes the position of command line arguments.
 SORT ? Sorts the contents of a file alphabetically or numerically.
  TIMEOUT ? Pauses the command processor for a specified number of
seconds.
 VERIFY ? Turns file verification on or off.
 VOL ? Displays the volume label and serial number of a disk
 APPEND ? Allows programs to open data files in specified directories
as if they were in the current directory.
 ASSOC ? Displays or modifies file extension associations
 ATTRIB ? Displays or modifies the attributes of a file.
 BREAK ? Controls the handling of extended keyboard CTRL+C and
CTRL+BREAK input.
 CHCP ? Displays or sets the active code page number.
 CHKDSK ? Checks a disk for errors and attempts to repair them.
 CLIP ? Redirects command output to the Windows clipboard.
 COMP ? Compares the contents of two files or sets of files.
 CONVERT ? Converts a FAT partition to NTFS.
 DEBUG ? Starts Debug, a command-line tool for testing and debugging
executable programs.
 DISKCOMP ? Compares the contents of two floppy disks.
 DISKCOPY ? Copies the entire contents of one floppy disk to another.
 DOSKEY ? Provides command-line editing and recall capabilities.
 FCBS ? Sets the number of file control blocks used by the system.
 GRAPHICS ? Turns graphics mode on or off.

External DOS Commands

 ATTR ? Displays or changes file attributes.
 BOOTCFG ? Configures, queries, or changes in the system startup
settings.
 CHOICE ? Allows for a choice to be made from a list of options.
 CIPHER ? Displays or changes the encryption of directories and files on
NTFS volumes.
 CMDKEY ? Creates, lists, or deletes stored user names and passwords
or credentials.
 COMMAND ? Starts a new instance of the command interpreter.
 DEBUGGER ? Starts the kernel debugger for debugging the operating
system.
 DEFRAG ? Optimizes the file system and increases the performance of
the computer.
  DISKPART ? Manages disks, partitions, and volumes from the
command line.
 DRIVERQUERY ? Displays a list of installed device drivers.
 EVENTCREATE ? Writes an entry to the application event log.
 EXIT ? Exits the command interpreter or batch script.
 FORMAT ? Formats a disk for use with Windows.
 FSUTIL ? Displays or configures file and volume properties.
 HELP ? Provides help information for Windows commands.
 IPCONFIG ? Displays network settings information.
 LINK ? Creates hard links and symbolic links to files and directories.
 MMC ? Starts Microsoft Management Console, a system administration
tool.
 NBTSTAT ? Displays statistics for NetBIOS over TCP/IP protocols.
 NET ? Manages network resources, such as computers, printers, and
services.
 OPENFILES ? Displays information about open files and the users who
opened them.
 PACKAGER ? Packages and unpackages files to and from CAB files.
 PING ? Verifies network connectivity.
 RDPSIGN ? Signs Remote Desktop Protocol (RDP) files.
 REMOTEACCESS ? Manages remote access connections and virtual
private network (VPN) connections.
 SC ? Configures and manages Windows services.
 SCHTASKS ? Schedules commands and programs to run at specific
times or events.
 SFC ? Scans and verifies the integrity of all protected system files and
replaces incorrect versions with correct Microsoft versions.
 SHUTDOWN ? Shut down or restart the local or remote computer.
 TASKLIST ? Displays a list of all running processes on the computer.

Common errors and how to avoid them

 Misspelling command names or parameters. Always double-check your
spelling and syntax before executing a command.
 Forgetting to use quotes around filenames or directories with spaces.
As mentioned earlier, DOS treats spaces as delimiters, so it's important
to enclose filenames and directories with spaces in quotes.
 Running commands from the wrong directory. Some commands may
not work correctly if you're not in the correct directory. Always make
sure you're in the right directory before executing a command.
 Using the wrong command for the task at hand. Not all commands are
appropriate for all tasks, so make sure you're using the right command
for the job.