Includes talking points

1. OPERATING SYSTEM
PRESENTATION
Group Assignment

2. Operating System Concepts
- An operating system (OS) acts as an interface between
the user and the computer hardware. It manages system
resources, provides common services for applications,
and facilitates communication between hardware and
software. Programs interact with the operating system
through code system calls to request services or
resources. CPU scheduling algorithms determine how
the CPU allocates time to running processes. Process
synchronization solutions ensure that multiple
processes can access shared resources without causing
conflicts.

3. Code System
Calls
• System calls are the primary
mechanism for a program to interact
with the operating system.
• They provide a controlled interface
for programs to access operating
system services and resources.

4. CPU Scheduling Algorithms
•CPU scheduling algorithms determine how the CPU allocates time to running processes.
•The goal of CPU scheduling is to maximize CPU utilization and provide fair and efficient service to all processes.
•Common CPU scheduling algorithms include:
• First-Come, First-Served (FCFS)
• Shortest Job First (SJF)
• Priority Scheduling
• Round-Robin (RR)
• Multilevel Queue Scheduling
CPU scheduling algorithms play a crucial role in operating system performance. They determine how the CPU allocates
running processes, impacting factors like system responsiveness, throughput, and fairness. Various CPU scheduling alg
exist, each with its advantages and disadvantages.
FCFS is a simple algorithm that schedules processes based on their arrival time.
SJF schedules processes based on their estimated execution time, aiming for minimal turnaround time.
Priority scheduling assigns priorities to processes, with higher-priority processes receiving more CPU time.
Round-Robin allocates CPU time in fixed-size slices (quantum) to processes,
providing a fair share of CPU time to all. Multilevel Queue Scheduling uses multiple queues with different scheduling algo
for various process types.

5. 1. First-Come, First-Served (FCFS):
1. Schedules processes based on their arrival time. Simple but can lead to starvation for short processes waiting
behind long ones.
2. Shortest Job First (SJF):
1. Schedules processes based on their estimated execution time (burst time). Aims for minimal turnaround time but
requires knowing execution times in advance, which may not always be accurate.
3. Priority Scheduling:
1. Schedules processes based on a priority assigned to each process. Higher priority processes get CPU time first.
Useful for prioritizing critical system tasks but can lead to starvation for lower priority processes if high-priority
processes are constantly present.
4. Round-Robin (RR):
1. Allocates CPU time in fixed-size slices (quantum) to processes. A process is preempted when its quantum expires,
and it moves to the back of the queue. Provides fairness and responsiveness but may lead to context switching
overhead if the quantum is too small.
5. Multilevel Queue Scheduling:
1. Uses multiple queues with different scheduling algorithms for various process types. Offers flexibility to prioritize
different process categories.

6. Process Synchronization Solutions
• Process synchronization ensures that multiple
processes can access shared resources without
causing conflicts.
• Conflicts can arise when multiple processes try to
access or modify the same data or resource
concurrently.
• Common process synchronization solutions include:
Process synchronization is essential for ensuring data
integrity and preventing race conditions in
multiprogramming environments. Race conditions
occur when the outcome of a program depends on the
unpredictable timing of events, such as multiple
processes accessing the same data at the same time.
Here's an overview of common process
1.Semaphores:
1. A general-purpose synchronization mechanism that
controls access to shared resources.
2. Semaphores use a non-negative integer value to
represent the number of available resources.
3. Processes can perform wait and signal operations
on semaphores.
4. Wait operation decrements the semaphore value,
potentially blocking the process if no resources are
available.
5. Signal operation increments the semaphore value,
potentially releasing a waiting process.

7. C CODE
EXAMPLE
(SEMAPHORE):

8. 2. Mutexes:
2. A special type of semaphore that allows only one process to access a shared resource at
a time.
3. Essentially a binary semaphore with a value of 1 (resource available) or 0 (resource in
use).
3. Monitors:
2. A high-level synchronization construct that encapsulates shared data and procedures
that operate on that data.
3. Monitors provide mutual exclusion and signaling mechanisms within a single unit.
4. Message passing:
2. Enables processes to communicate and synchronize their execution by exchanging
messages.
3. Processes can send and receive messages through queues, ensuring proper ordering
and coordination.

9. 1. Inter-Process Communication (IPC):
• Concept: IPC allows processes to exchange data and
synchronize their execution.
• Benefits: Enables collaboration between processes, data
sharing, and efficient resource utilization.
• Common IPC mechanisms:
Shared Memory: Processes access a common memory
segment for data exchange.
• Note: Shared memory use is discouraged in modern
systems due to potential security risks and complexity.
Consider alternatives like message passing for safer and
more modular IPC.
• Message Passing: Processes send and receive messages
through queues or mailboxes.
• Semaphores and Mutexes: Used for synchronization and
controlling access to shared resources (covered in Process
Synchronization).
• Pipes and FIFOs: Allow unidirectional data flow between
processes.
• Sockets: Enable communication between processes on different

10. 2. Multi-Threading:
• Concept: A single process
can have multiple threads
of execution, allowing for
concurrent execution
within the process.
• Benefits: Improved
responsiveness, efficient
handling of I/O-bound
tasks, and better utilization
of multi-core processors.

11. - 3. Process Creation/Termination:
• Process Creation: The operating system creates a new process based on an existing program.
Common system calls include fork() (Unix-like systems) or CreateProcess() (Windows).
• Process Termination: A process can terminate normally on its own or be terminated by the
operating system due to various reasons (e.g., errors, user request). System calls
like exit() or TerminateProcess() are used for termination.
- 4. Process Synchronization (Covered Previously):
• Concept: Ensures that multiple processes can access shared resources without causing conflicts.
• Mechanisms: Semaphores, mutexes, monitors, message passing.
- 5. Deadlock Handling:
• Concept: A state where multiple processes are waiting for resources held by each other, preventing
any progress.
• Prevention: Careful resource allocation strategies (e.g., ordering access requests, holding and
waiting).
• Detection: Algorithms to identify deadlocks when they occur.
• Recovery: Techniques to restart processes or preempt resources to break the deadlock.

12. Memory Management:
• Concept: The operating system manages the allocation and use of primary
memory (RAM) for efficient program execution.
• Responsibilities:
• Keeping track of allocated and free memory blocks.
• Allocating memory to processes when needed.
• Deallocating memory when processes terminate or no longer require it.
• Protecting memory spaces of different processes to prevent interference.
• Common Memory Management Techniques:
• Fixed-size partitioning: Divides memory into fixed-size blocks. May lead to
internal fragmentation.
• Variable-size partitioning: Allocates memory blocks of varying sizes based
on process needs. Can suffer from external fragmentation.
• Paging: Divides both physical memory and logical address space (process
address space) into fixed-size blocks called pages. Provides flexibility and
reduces fragmentation.
• Segmentation: Divides logical address space into variable-size segments
based on logical units (code, data, stack) and maps them to non-contiguous
physical memory frames. Improves memory utilization for programs with
logical groupings.

13. Virtual Memory Management
• Concept: Allows processes to have a larger virtual address space than the available physical memory (RAM).
• Benefits:
• Enables running programs exceeding physical memory size.
• Simplifies memory management for programmers as they can use a larger logical address space without
worrying about physical limitations.
• Mechanism: Uses a combination of hardware (Memory Management Unit - MMU) and software (page table) to
translate virtual addresses used by a process into physical memory addresses.
• Process:
• Program references a virtual address.
• MMU intercepts the address and checks the page table.
• Page table entry indicates if the page is present in physical memory (page hit) or on disk (page fault).
• On a page hit, the physical address is retrieved from the page table, and the data is accessed.
• On a page fault, the operating system swaps a less-used page from physical memory to disk and loads
the requested page from disk into physical memory. The page table is updated.
• The process resumes execution using the newly loaded page.

15. Memory Mapping
• Concept: Technique that maps a file or a
region of a file directly into the virtual address
space of a process.
• Benefits:
• Efficient access to file data without explicit
read/write operations.
• Allows processes to treat file content as
part of their memory space.
• Mechanism: The operating system
establishes a mapping between file data on
disk and a virtual memory region. Any access
to that virtual address range triggers access to
the corresponding file location.

16. File System Management Aspect Windows Linux MacOS Real-Time OS
Access Method NTFS Ext4 APFS
Optimized for
deterministic
access
Sequential,
Random, Direct
Access
Read, Write,
Execute
Permissions
Hierarchical,
POSIX-based
Permissions
Advantage
- Support for large
volumes and files
- Good
performance with
large files
- Efficient
snapshotting
capability
- Predictable
access time for
real-time tasks
Disadvantage
- Proprietary,
limited
interoperability
- Fragmentation
issues with
extended use
- Limited
compatibility with
non-Apple systems
- Limited support
for large-scale
storage
•Windows: NTFS provides versatile access methods, but its proprietary nature limits
interoperability. Drive letter-based organization simplifies navigation.
•Linux: Ext4 offers robust performance and extensive permissions, though
fragmentation and complexity may arise with prolonged use.
•MacOS: APFS introduces hierarchical organization and POSIX-based permissions,
enhancing file tagging for improved organization.
•Real-Time OS: Prioritizes deterministic access for time-sensitive applications, ensuring
predictable execution times for critical processes.

17. File System Management (contd.) Aspect Windows Linux MacOS Real-Time OS
Organization
Hierarchical with Drive
Letters
Root-based
Hierarchical Structure
Unix-based Structure
Optimized for
Efficiency and
Deterministic Access
(e.g., C:, D:)
Starting from Root
Directory (/)
Starting from Root
Directory (/)
Advantage
- Easy navigation with
drive letters
- Robust and flexible
directory structure
- Enhanced file
tagging for
organization
- Customized for real-
time application needs
Disadvantage
- Limited scalability
and flexibility
- Complexity for
novice users
- Limited cross-
compatibility
- Complexity in
implementation for
general-purpose use
•Windows: Drive letter-based hierarchical structure facilitates easy navigation but limits
scalability and flexibility.
•Linux: Root-based hierarchical structure offers robustness but complexity may deter
novice users.
•MacOS: Unix-based structure with file tagging system enhances organization but lacks
cross-compatibility.
•Real-Time OS: Customized organization optimizes efficiency and deterministic access
for real-time applications.

18. File System Management (contd.)
Aspect Windows Linux MacOS
Real-Time
OS
Sharing
Supports
SMB, NFS
NFS, Samba,
SSHFS
AFP, SMB
Customized
for Real-Time
Networking
Protocols
Advantage
- Native
support for
SMB and
NFS
- Various
options for
network file
sharing
- Smooth
integration
with Apple
devices
- Tailored for
real-time
networking
requirements
Disadvantag
e
- Vulnerable
to security
breaches
-
Configuration
complexity
- Limited
support for
non-Apple
devices
- Limited
compatibility
with standard
protocols
•Windows: Supports SMB and NFS for network file sharing, but vulnerability to
security breaches is a concern.
•Linux: Various sharing options including NFS, Samba, and SSHFS provide
flexibility, though configuration complexity may arise.
•MacOS: Integration with AFP and SMB ensures smooth collaboration within the
Apple ecosystem, but compatibility with non-Apple devices is limited.
•Real-Time OS: Tailored sharing solutions prioritize real-time networking protocols,
ensuring efficient communication in time-sensitive applications.

19. Secondary Storage Management Aspect Windows Linux MacOS Real-Time OS
Architecture
Layered with File
System Drivers,
Disk Drivers,
Storage Stack
Modular with VFS
Layer, File
Systems, Block
Device Drivers
Layered with VFS
Layer, File
Systems, I/O Kit
Tailored for Real-
Time Performance
Advantage
- Well-structured
and modular
architecture
- Extensive
support for
various file
systems
- Seamless
integration with
hardware
- Optimized for
real-time
performance and
reliability
Disadvantage
- Complex
architecture
leading to
potential instability
- Compatibility
issues with
proprietary
hardware
- Limited
customization
options for
advanced users
- Limited
scalability for
general-purpose
use
•Windows: Layered architecture with file system drivers, disk drivers, and storage
stacks ensures structured management but may lead to complexity and potential
instability.
•Linux: Modular architecture centered around VFS layer offers flexibility but
compatibility issues with proprietary hardware may arise.
•MacOS: Layered architecture similar to Unix systems integrates components like
VFS and I/O Kit, ensuring seamless hardware integration but limiting customization
options.
•Real-Time OS: Designed for real-time performance, ensuring timely data access
and reliability, but may lack scalability for general-purpose use.

20. Secondary Storage Management (contd.) Aspect Windows Linux MacOS Real-Time OS
Accessing
DMA,
Programmed I/O
Buffered I/O,
Asynchronous
I/O, Direct I/O
Asynchronous
I/O, Memory-
mapped Files
Optimized for
Deterministic
and Real-Time
Requirements
Advantage
- Efficient data
transfer methods
- Versatility in I/O
operations
- Enhanced
performance
with
asynchronous
I/O
- Predictable
access times for
critical tasks
Disadvantage
- Complexity in
managing direct
memory access
- Complexity in
asynchronous
I/O setup
- Increased
system resource
utilization
- Limited support
for certain
storage devices
•Windows: Utilizes DMA and programmed I/O for efficient data transfer, but
managing direct memory access can be complex.
•Linux: Offers a range of disk access techniques catering to diverse I/O
requirements, though setup complexity may deter users.
•MacOS: Employs asynchronous I/O and memory-mapped files for enhanced
performance and flexibility but may lead to increased system resource
utilization.
•Real-Time OS: Optimized disk access methods ensure predictable execution
times for critical tasks, but limited support for certain storage devices may be a
drawback.

21. Secondary Storage Management (contd.)
Aspect Windows Linux MacOS
Real-Time
OS
Disk
Scheduling
CFQ,
Deadline
Scheduler
CFQ,
Deadline,
CFS
Anticipatory,
Deadline
Scheduler
Priority-based
Scheduling
for Real-Time
Tasks
Advantage
- Effective
disk I/O
management
- Versatility in
disk
scheduling
algorithms
- Optimized
disk
performance
- Ensures
timely
execution of
critical tasks
Disadvantag
e
- Complexity
in selecting
appropriate
scheduler
- Fairness
issues with
certain
scheduling
algorithms
- Increased
latency in
certain
scenarios
- Overhead in
managing
priority levels
•Windows: Employs CFQ and Deadline schedulers for effective disk I/O
management, ensuring balanced performance, though complexity in selecting
appropriate scheduler may arise.
•Linux: Provides a variety of scheduling algorithms balancing fairness and
efficiency, though fairness issues with certain algorithms may arise.
•MacOS: Utilizes Anticipatory and Deadline schedulers to optimize disk I/O
performance, reducing latency but increasing system overhead.
•Real-Time OS: Priority-based scheduling ensures timely execution of time-
sensitive operations, but complexity in managing priority levels may be a concern.

22. Biblography.
Mwiinga, P. (2023). Operating System.
Idris, M. (2021). A Comparative Study of Operating
Systems: Case of Windows, Mac and Linux.
Wang, J. (2017). Real‐Time Operating Systems. DOI:
10.1002/9781119420712.ch3.
Shastri, S., Mansotra, V., & Sharma, A. (2016). A
Comparative Analysis of Disk Scheduling Algorithms.
Markatos, E., Katevenis, M., Pnevmatikatos, D., & Flouris,
M. (1999). Secondary Storage Management for Web
Proxies.

23. z
How OS is responsible the i/o management?
Input, output and processing are three major and primary operations .
OS organizes i/o operations along with respective associated i/o
devices .
Each device have its own drivers software. Once they installed on a
computer, they make permanent contact with the OS.
After this communication the os take control on these drivers to
control their respective devices.
For this some inbuilt system software are already available in an os.
Every deice can perform multiple functions in every different state.
1.At which time which device perform which operation,
2.How this execution take place,
3.How to arrange requests made by devices
Is comes in input output management.
CPU MEMORY
I/O DEVICES
INPUT/OUTPUT MENAGEMENT

24. z
NETWORK OPERATING SYSTEM
A network operating system (NOS) is a type of operating
system that enables multiple users to connect to a single
computer or server
TWO PRIMARY PARTS :
 Client
 Server
FEATURES:
•Highly stable centralized servers.
•Security concerns are handled through servers.
•New technologies and hardware up-gradation are easily
integrated to the system.
•Server access are possible remotely from different
locations and types of systems.

25. z
REAL TIME OPERATING SYSTEM
These types of Operating systems are used in real-time systems.
The response time to process and respond to inputs is very small
Mostly used in those systems in which the results of the computations are used to
influence a process while it is executing.
Real-time systems are used at those places where strict time requirements are
followed such as missile systems, air traffic control systems, robots, etc.
Some kinds of sensors are used to detect any external foreign event except
execution.
In between execution if any external event occurs, sensors detect it and pass on
the information to the computer.
The sensor produces the signal that is interpreted by the operating system as an
interrupt.
On receiving an interrupt, the operating system invokes a specific process or a set
of processes to serve the interrupt.

26. z
DISTRIBUTED OPERATING SYSTEM
 Multiple computers shares a single online operating system.
 These autonomous interconnected computers communicate with each
other using a shared communication network.
 These computers have their own memory unit and CPU.
 These are referred to as loosely coupled systems or distributed systems.
 These system’s processors differ in size and function.
 Advantages of Distributed Operating System:
• Failure of one will not affect the other network communication, As
all systems are independent from each other
• Electronic mail increases the data exchange speed
• Since resources are being shared, computation is highly fast and durable
• Load on host computer reduces

27. z
PROTECTION AND SECURITY IN OS
protection Security
Protection deals with who has access to the
system resources.
Security gives the system access only to authorized
users.
Protection tackles the system's internal threats. Security tackles the system's external threats.
Protection addresses simple queries. More complex queries are addressed in security.
It specifies which files a specific user can access
or view and modify.
It defines who is permitted to access the system.
An authorization mechanism is used in protection.
Encryption and certification (authentication)
mechanisms are implemented.
Protection provides a mechanism for controlling
access to processes, programs, and user
resources.
While security provides a mechanism to safeguard
the system resources and the user resources from
all external users.

28. z
Case study
Company XYZ, an industrial automation equipment manufacturer, must choose an operating
system (OS) for their new product line. Key considerations include robustness, real-time
processing, user interface, and compatibility.
 Windows: Widely used with extensive software support, but lacks real-time capabilities and
is prone to viruses, posing risks for critical applications.
 Linux: Customizable, open-source, with real-time capabilities through specialized kernels.
Offers robust security but may require additional resources for development.
 MacOS: User-friendly, Unix-based, but lacks real-time capabilities and has limited hardware
and software compatibility for industrial use.
 Real-Time OS (RTOS): Designed for time-sensitive applications, ensures deterministic
behavior and precise timing control. Limited software compatibility but reliable in critical
environments.
After deliberation, Company XYZ selects Linux with a real-time kernel. This choice combines
Linux's flexibility and security with real-time capabilities, meeting their requirements for industrial
automation.