Computer Introduction (Operating Systems)-Lecture06

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Lecture No. 6: Operating Systems
Lecturer: Dr. Mazin Alkathiri
Department of Information Technology
,
College of Computers
Seiyun University
Nov , 2024

Operating System
• An Operating System can be defined as an interface between user
and hardware. It is responsible for the execution of all the processes,
Resource Allocation, CPU management, File Management and many
other tasks.
• The purpose of an operating system is to provide an environment in
which a user can execute programs in convenient and efficient
manner.

• A Computer System consists of:
• Users (people who are using the computer)
• Application Programs (Games, Video player, Browsers, etc.)
• System Programs (Shells, Editors, Compilers, Databases etc.)
• Operating System ( A special program which acts as an interface between user
and hardware )
• Hardware ( CPU, Disks, Memory, etc)
Structure of a Computer System

• An Operating System can be defined as an interface between user
and hardware. It is responsible for the execution of all the processes,
Resource Allocation, CPU management, File Management and many
other tasks.
• The purpose of an operating system is to provide an environment in
which a user can execute programs in convenient and efficient
manner.
• Operating system controls and coordinates the use of hardware among application programs.
Operating System

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Key Roles of an Operating System
1. Resource Management
2. Process Management
3. Memory Management
4. File System Management
5. Device Management
6. User Interface (UI)

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1. Resource Management:
• The OS allocates resources like CPU time, memory, and storage to various
applications, balancing demand and availability.
• For example, if multiple programs are running simultaneously (like a browser, a text editor, and a
video player), the OS ensures each program receives enough CPU time without one program
completely dominating.
2. Process Management:
• An OS is responsible for creating, scheduling, and terminating processes (a process
is an instance of a program in execution).
• When you open a web browser, the OS creates a process for that program. If you open multiple
tabs, the OS may manage each tab as a separate process to ensure stability. If one tab crashes, it
won’t affect the other tabs.
3. Memory Management:
• It keeps track of each byte in a computer's memory, determining how much
memory to allocate to processes, and freeing it up when it's no longer needed.
• For example, when you open an image editor to edit a high-resolution photo, the OS allocates
more memory to handle the file. When you close the program, it deallocates that memory.

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4. File System Management:
• The OS manages files on your system, providing an organized way to
store, retrieve, and manipulate data.
• For example, when you save a document, the OS organizes and places that file
within your file system, allowing you to retrieve it later.
5. Device Management:
• It manages the communication between software and hardware
components.
• When you connect a printer, the OS helps in sending the print command from
your application to the printer hardware.
6. User Interface (UI):
• Many operating systems provide a Graphical User Interface (GUI),
allowing users to interact with the system in a visual and intuitive way.
• Examples of GUI-based OSs are Windows, macOS, and Linux distributions with a
desktop environment (like Ubuntu's GNOME or KDE Plasma).

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Examples of Operating Systems
• Microsoft Windows: Popular for its user-friendly interface and
compatibility with a vast number of applications, widely used in
personal and business environments.
• macOS: Developed by Apple for its line of Mac computers, known for
its sleek design and stability.
• Linux: An open-source OS available in different distributions (e.g.,
Ubuntu, Fedora, Debian) commonly used in servers and development
environments due to its flexibility and security.
• Android and iOS: Operating systems for mobile devices, managing
hardware resources on smartphones and tablets.

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MS-DOS (Microsoft Disk Operating System)
• is an early operating system developed by Microsoft, which dominated
the personal computer market during the 1980s and early 1990s. While
it's no longer widely used, MS-DOS played a foundational role in the
development of operating systems and computing as a whole.
• Key Features and Characteristics of MS-DOS
1. Single-tasking System:
2. Single-user System:
3. Command-line Interface (CLI):
4. File System (FAT):
5. Low-level Hardware Access:

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MS-DOS Commands: Examples
Here are a few common MS-DOS commands that illustrate how users interacted with
the OS:
•dir: Lists files and directories in the current directory.
•copy: Copies files from one location to another.
•Example: copy file1.txt C:backup would copy file1.txt to the backup folder.
•del: Deletes a file.
•Example: del oldfile.txt deletes oldfile.txt from the current directory.
•cd: Changes the current directory.
•Example: cd documents would move to the documents directory.

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Limitations of MS-DOS
• No Multitasking or Memory Management:
• No Built-in Networking Support:
• Security Limitations:
• Lack of a GUI:

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Types of Operating Systems
• Single-tasking and Multi-tasking OS:
• Single-tasking OS: Can only execute one task at a time.
• Multi-tasking OS: Can handle running multiple applications simultaneously by rapidly switching between them.
• Single-user and Multi-user OS:
• Single-user OS: Only one user can operate the computer at a time.
• Multi-user OS: Supports multiple users, each with a separate session, often found in server environments.
• Distributed OS:
• Manages a group of independent computers and makes them appear as a single cohesive system, allowing for
distributed computing.
• Real-Time OS (RTOS):
• Designed for real-time applications that require immediate response, such as in medical systems or automotive
controls.
• Embedded OS:
• Specially designed for embedded systems like those in cars, washing machines, or industrial machines.

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Examples in Daily Use
• Smartphones: Both Android and iOS are designed to handle
multimedia, connectivity, and multitasking while being energy-
efficient. They manage background tasks like email syncing,
notifications, and app updates.
• ATMs and Kiosks: ATMs use a type of real-time operating system to
handle transactions reliably and securely, with a strict focus on user
inputs and quick response to commands.
• Desktop Computers: A desktop OS like Windows 10 or macOS offers
features for multi-tasking, user account management, and security,
enabling users to work on documents, browse the web, and run
complex applications like games or design software.

 is accountable for the formation and deletion of files and directories.
 manages the process of deletion, suspension, resumption, and synchronization.
 manages memory space by allocation and de-allocation.
 stores, organizes, names and protects the existing files.
 manages all the components and devices of the computers system including
modems, printers, plotters, etc.
 In case, if any device fails, the operating system detects and notify.
 protects from destruction as well as from unauthorized use.
 facilitates the interface to user and hardware.
Applications of Operating System

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Conclusion
• Operating Systems are the backbone of modern computing.
• They enable users to interact with complex hardware in an accessible
way, handle multiple tasks seamlessly, and manage essential
resources.
• Whether it's the OS on your smartphone, laptop, or a supercomputer,
each OS type has specific features tailored to optimize performance
for its intended purpose.

Computer Introduction (Operating Systems)-Lecture06

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