Operating System Concepts

Operating Systems Concepts

• An Operating System (OS) course is a foundational component of a computer related degree program.
• Understanding of how operating systems work is essential for understanding the computational foundation of modern technology.
• Concepts like process scheduling, memory management, file systems, and concurrency are critical for practical implementations.
• Many applications require low-level interactions with the operating system for resource management, file handling, and optimization.
• Topics like synchronization, deadlock resolution, and multitasking challenge students to think critically and devise solutions to complex problems.
• An OS course serves as a prerequisite for understanding advanced topics like distributed systems, networking, cybersecurity, and cloud computing.
• IT professionals often need to manage, configure, and secure operating systems.
• Knowing how an OS works helps students identify performance bottlenecks, debug system-level issues, and optimize applications for specific platforms or environments.
• Concepts like virtualization, containerization, and real-time systems are rooted in OS principles.
• Employers value candidates who understand how systems work under the hood.
• OS knowledge is applicable across a range of platforms, from personal computers and servers to embedded systems and mobile devices.
• An OS course equips students with the fundamental skills and knowledge needed to excel in computer technology.
• An Operating System (OS) is an interface between the user and the hardware.
• Operating systems manage computer hardware resources

Operating System

• An operating system provides an environment for users to perform tasks conveniently and efficiently.
• The operating system is a collection of software that manages computer hardware resources.
• It provides common services and platforms required by computer programs.
• The operating system acts as an interface between the user and computer hardware.
• It's a well-organized collection of programs managing computer hardware.
• It is system software responsible for the smooth functioning of the computer system.
• An operating system performs essential tasks like file and memory management.
• Other important and basic tasks are process management, handling input/output, and the control of peripheral devices like printers and disk drives.

Structure of a Computer System

• A computer system generally includes computer users, application software, system software, and computer hardware.
• Computer users are people or devices using the system.
• Application software is used directly to perform activities, such as browsers and video players.
• Application software is written in languages like Python, Java, and C++.
• System software, like operating systems, compilers, and shells, is more complex and closer to the hardware.
• System Software includes Microsoft Windows, macOS, and Linux
• Computer hardware consists of physical devices like monitors, keyboards, CPUs, disks, and memory.
• Computer hardware is the body of a computer system
• The operating system is the soul which brings the system to life.

System vs Application Software

• A computer system cannot be used without an operating system.

Operating System Examples

• Commercial operating systems, like Windows 8 and 10, require payment.
• Linux is Unix-based and was first released on September 17th, 1991 by Linus Torvalds.
• Linux has 30+ variants like Fedora, OpenSUSE, CentOS, and Ubuntu, mostly available for free.
• Enterprise versions of Linux require a license fee.
• MacOS is a Unix operating system developed and marketed by Apple Inc. since 2001.
• iOS is a mobile operating system created by Apple Inc. for mobile devices like iPhone and iPad.
• Android is a mobile operating system based on a modified version of the Linux kernel.
• Android is open-source software and designed for touchscreen devices like smartphones and tablets.
• Older operating systems include Solaris, VMS, OS/400, AIX, z/OS, and DOS.

Operating System Summary

• An operating system is an interface between a computer user and computer hardware.
• The OS performs basic tasks like file, memory, and process management.
• it controls input and output, and peripherals such as printers and disk drives.
• The main function is to enable applications to interact with hardware and manage system resources.
• The core components of the operating system is called the kernel.

Functions / task of an Operating System

• Primary Memory Management
• Secondary Storage Management
• Processor Management
• Process Management
• Device Management
• File Management
• Network Management
• Security Management
• Control over system performance
• Job accounting

Main Memory Management

• It allocates and deallocates memory space as it is needed. It is required that a program be in main memory for it to be executed.
• Memory is a large array of words or bytes, each with its own address.
• It is a repository of data shared quickly between the CPU and I/O devices.
• Main memory is a volatile storage device, losing its content when system power goes down or system failure occurs.
• Memory management aims to maximize memory utilization on the computer system.
• It tracks primary memory, determines used and unused portions, and in multiprogramming, it decides which process gets what memory.
• It allocates memory when a process requests it and de-allocates memory when no longer in use or terminated.

Secondary Storage Management

• The computer system executes programs that, along with accessed data, must be in main memory during execution.
• Since main memory is limited the computer system needs secondary storage to back it up.
• Most computer systems use disks as the main on-line storage medium for programs and data.
• Most programs, such as compilers and formatters, are on disk until loaded into memory for processing.
• Key tasks of secondary storage management include file system, maintaining directories, handling read/write operations, free space and storage allocation, and disk scheduling.

Processor Management

• Processor management involves allocating CPU time to different processes for execution.
• The key tasks are keeping track of the processor and process status, undertaking scheduling processes, managing execution order, allocating processor CPU to a process, deallocating when no longer required, and ensuring efficient CPU use.

Process Management

• Process management handles and oversees the execution of processes.
• A program in a running state is considered as a process.
• The process needs certain resources like memory and CPU time to accomplish its tasks.
• It creates, loads, executes, suspends, resumes, and terminates processes.
• The OS switches the system among multiple processes in main memory.
• Provides synchronization mechanisms to control concurrent data access to keep it as consistent.
• It allocates or deallocates resources to prevent or avoid deadlock situations.

I/O Device Management

• One job is to hide peculiarities of specific hardware devices from users.
• Device communication is managed via respective drivers.
• Input and output devices are controlled and coordinated.
• It provides an abstract level for hardware devices and hides details to ensure proper device use, prevent errors, and provide a convenient programming environment.

File Management

• File management organizes and controls files within a file system
• File management is a key service of the operating system.
• The file system is organized into directories for navigation and usage.
• A file is defined as a set of correlated information in varied formats, such as alphabetic or numeric.
• It consists of a sequence of bits, bytes, lines, or records with meanings.
• Key tasks include file creation, deletion, and the directory folder management, reading writing, writing organizing, mapping, managing permissioning, and providing backup on stable media.

Network Management

• Network management has different components
• It manages and administers the computer network
• A computer network is a collection of various types of devices connected with each other
• It involves fault analysis, service quality maintenance, provisioning of networks, and performance management
• It keeps your network healthy for efficient communication between different computers
• Key tasks include network protocols implementation, managing network connections, facilitating data transfer, ensuring network security, and provisioning access to users.

Security Management

• It ensures that the system and its resources are protected
• Primarily responsible for all the computer system's tasks and activities
• Mechanisms are needed to verify that the files, memory segments, CPU, and other resources are in operation on processes the have authorization by the operating system.
• Security Management manages the access of users, processes, and programs to resources by defining computer controls and enforcement methods.
• Memory addressing ensures a process executes only within its address space.
• A timer ensures no process monopolizes the CPU.
• I/O operations are restricted to protect integrity of peripheral devices.
• Passwords, and encryptions and the like prevent unauthorized access to programs and data.
• The OS ensures controlled access to system resources, protects external I/O devices from invalid access, provides user authentication, and facilitates encryption.

Performance and Job Accounting

• Monitors system performance to optimize
• Logging resource consumption by running processes
• Maintaining the records of all use
• It adjusts system parameters for efficiency.
• Tracks resource usage for billing, auditing, or performance analysis.

Command Interpreter System

• One of the most major components is the command interpreter.
• The Command Interpreter runs users commands by calling more underlying system commands or calls.
• It allows human users to interact with the OS.

Additional Information

• An OS is a complex software with multiple activities that collectively provide a stable and efficient environment for applications and managing hardware resources.

Multiprogramming

• Multiprogramming is an operating system strategy where multiple programs are loaded into memory at the same time where they share the CPU
• A purpose is to increase CPU utilization and system-wide throughput by overlapping
• CPU and I/O operations
• It aims to maximize CPU utilization and keep the CPU ready, even if an individual program is waiting for in or out operations
• In modern computing systems, several concurrent applications will have to be executed

Multiprogramming in a computer system

• The operating system is responsible with managing processes to ensure efficiency
• One of the most important functions in process is multiprogramming
• There is usually multiple processes awaiting execution, which means the processes are waiting for some CPU allocation
• The waiting process may also be known as jobs
• Main memory can be too small to fit all jobs
• Before making their way to main memory
• Jobs are initially initially kept in a job pool
• Job pool contains all processes that are a waiting allocation to main and
• Memory and CPU
• The CPU select a job from the pull and transfer it to main and subsequently starts to execute
• CPU has the processor execute job until there is a interuption from some external factor, the current job goes to a in/out task
• In a non-multiprogrammed system as soon as on job to leave CPU/process, its the case that the CPU becomes idle
• In a multiprogramming system as soon as one job leaves CPU/process, its the case that OS picks the next job from the memory (waiting queue) gives CPU and starts the execution

Multiprocessing

• Multiprocessing involves utilizing processors or CPU cores to execute multiple tasks concurrently.
• The main goal of multiprocessing is to improve overall system performance/ parallelizing the processing of tasks and distributing computer workload over multiple processors.
• Symmetric Multiprocessing (SMP) and Asymmetric Multiprocessing (AMP)

Symmetric Multiprocessing (SMP)

• All processes are considered equal with equal access
• They share common memory space to execute any task for system
• Task that are dynamic are typically distribute between processes
• Ensure equal amounts of work
• The system remains efficient
• Processor obtain work that has balance use if sources
• System required synchronize mechanisms to coordinate activities/accessing when shared resources

Asymmetric Multiprocessing (AMP)

• Task may be a specific role/task assigned on process
• One processor handles I/O operations
• While another focuses on computation
• System may have less synchronization because its not involved in decision process
• In the AMP has designed the master processor
• It distributed tasks to other processors
• Which were considered as slaves
• Flexibility and adaptability allows the system to remain efficient at all times

Multiprocessing computer usage

• A system with one process executes is called a Uni processor
• Muiltiprocessing is more than 2 CPUs (processors) within a computer
• System support for more than processors with in a computer
• Processes executes at the same time

Multi-processors sharing

• Computer bus
• clock
• Memory
• Peripheral devices
• Use with multiple procession
• Minuses and pluses of systems
• Those types of systems work at high speed that is a amount of data
• System can save money procession, can share power supplies
• Increased