Operating System Concepts

Operating Systems Concepts

• Operating systems manage computer hardware and software.
• This material explores the concepts, functions, and evolution of operating systems.

Learning Objectives

• Innovations in operating system development.
• The basic roles of operating systems.
• Understanding the functions of major operating system software subsystem managers.
• Types of machine hardware that operating systems run on.
• Differences among batch, interactive, real-time, hybrid, and embedded operating systems.
• Multiprocessing and its impact on operating system software's evolution.
• Virtualization and core architecture trends in new operating systems.

Operating System Defined

• A computer system consists of software and hardware (physical machine and electronic components).
• An Operating System is part of the computer system software that manages the hardware and software, including files, devices, memory sections, and processing time.
• It controls system access and usage.

Operating System Software

• There are four essential subsystem managers: Memory, Processor, Device, and File Manager.
• The Network Manager is a fifth subsystem manager implemented in modern operating systems, it handles networking tasks, discussed in latter chapters.
• The User Command Interface allows the user to communicates to the operating system by issuing commands.
• Essential managers provide support for the user command interface and may vary between versions.
• Each processes has a unique role and operates with other managers.
• Managers continuously monitor resources while enforcing resource and allocation policies.

Network Manager

• Integrates networking capabilities into Operating Systems.
• Networking provides a way for users to share resources while retaining user access controls.
• Resources include both hardware (CPUs, memory, printers) and software (compilers, applications, data files).

Main Memory Management

• Manages main memory (RAM), preserves space used by the OS, checks validity, sets up a memory tracking table, & deallocates memory.
• Memory tracking tables track usage of memory sections and are needed in a multiuser environment.

Processor Management

• Manages the allocation of the Central Processing Unit (CPU).
• Process status means an instance of program execution.
• The Job Scheduler handles jobs as they enter the system
• The Process Scheduler manages each process within those jobs.

Device Management

• Monitors all resources like devices, channels, and control units.
• Responsibilities include selecting resource allocation methods based on scheduling policies. Responsibilities also include allocating, starting operation, and deallocating devices

File Management

• Responsible for tracking files like data and program files.
• Enforces user/program resource access and modification restrictions based on predetermined access policies.
• Allocates resources.
• The process of opening files, and deallocating them by closing..

Cooperation Issues

• Essential managers perform tasks and harmonize with other managers, which requires precision.
• Work is not completed in isolation by any single manager.
• Sharing resources and controlling user access is provided by the network manager function.

History of Machine Hardware

• Hardware components include main memory (RAM), input/output (I/O) devices, and the central processing unit (CPU).
• RAM (Random Access Memory) handles storage and execution of data and instructions.
• I/O devices are peripheries.
• CPU controls interpretation and execution of instructions.
• Early computers classified by capacity and price.

Mainframe

• Large machines with significant memory capacity.
• The 1964 IBM 360 model 30 required an 18-square-foot air-conditioned room only had 64K of internal memory and costed $200,000.
• Early applications were limited to large computer centers.

Minicomputer

• Developed for smaller institutions
• Compared to mainframe, it smaller and cheaper.
• Current minicomputers are referred as midrange computers with capacity in between mainframes and microcomputers.

Supercomputer

• A massive machine
• Developed for military operations and weather forecasting.
• The Cray supercomputer can use from 6-1000 processors and perform 2.4 trillion floating-point operations per second.
• Utilized for scientific research and customer support/product development.

Microcomputer

• Developed for single users in the late 1970s.
• Microcomputers by Apple and Tandy had very little memory with a maximum capacity of 64K and were notable for their single-user status.

Workstation

• The most powerful Microcomputers
• Developed for commercial, educational, and government enterprises and networked together.
• Support engineering and technical users with massive mathematical computations, computer-aided design (CAD) as example applications and it requires powerful CPUs, large memory, or graphic displays.

Servers

• Provide specialized services
• Often used by other computer or client/server networks, performing critical network tasks, such as print, internet, and mail servers.

Advances in Computer Technology

• Physical size, cost, and memory capacity have changed dramatically.
• Networking is an integral part of modern computer systems.
• Information delivery is a feature of mobile societies
• By processor instead of memory capacity.
• Computing power rises exponentially, according to Moore's Law.

Types of Operating Systems

• Five categories: Batch, Interactive, Real-time, Hybrid, and Embedded.
• Response time and data entry method distinguish OS types.

Batch Systems

• Batch systems use punched cards or tape for input.
• Efficiency is measured in throughput.

Interactive Systems

• Interactive systems have faster turnaround times than batch systems but slower than real-time systems.
• Time-sharing software was designed for interactive systems.

Real-time Systems

• Reliability is key for real-time systems, which used in time-critical environments, such as space flights, industrial processes, medicine, etc.
• They are fast, time limit sensitive and must be 100% responsive.

Hybrid Systems

• Hybrid systems combine batch and interactive processing.
• Batch programs run in the background while maintaining interactive processing, where the interactive load is light.

Embedded Systems

• Embedded systems are placed inside other products, adding features and capabilities and are not interchangeable.
• They perform a specific set of programs, require small kernels, and flexible function capabilities.

1940s - First Generation Operating Systems

• Computers used vacuum tube technology
• There was no standard OS software.
• Each program included every instruction needed to perform tasks.
• Low machine utilization resulted in CPU data processing for a fraction of available time.
• Early programs were conservative with resources, and understandability was not a priority.
• In 1945 Harvard's Mark 1 identified its first computer "bug" , the term is still in use today.

1950s - Second Generation Operating Systems

• Focused on cost of effectiveness.
• Two adopted improvements were:
  • Human operators
  • Job scheduling grouping programs with similar requirements
• I/O devices speed increases.
• Records blocked before retrieval of storage.
• Linkage editors were used to add access methods to object code.
• Buffers between I/O and CPU reduced speed discrepancy.
• Timer interrupts allowed job-sharing.

1960s - Third Generation Operating Systems

• Faster CPUs causes problems with slower I/O devices.
• Multiprogramming allowed many programs to load at one time.
• Program scheduling continues today.
• Few data management advances and total operating system customization to suit user needs.

1970s Computer tech

• Faster CPUs created problems with slower I/O devices and physical capacity limitations.
• Multiprogramming increased CPU and virtual memory was developed to solve physical limitations.
• became a popular tool.
• Database management software tools introduced.
• Programs started using English-like words, modular structures, and standard operations.
• The Cray I supercomputer, introduced in 1976, boasted 8MB and a world record for operations per second.

1980s Hardware tech

• Cost/performance ratio improvement of computer components.
• flexible hardware (firmware).
• Multiprocessing allowed parallel program execution.
• Evolution of personal computers and evolution of high-speed communications.
• Distributed processing and networked systems introduced.

1990s Internet tech

• Demand for Internet capability sparked networking capability.
• Tighter security demands increased to protect hardware and software and multimedia applications became more demanding.

2000s Design features

• Design focused on multimedia applications and internet access.
• Features to support client/server computing.
• Increasing demands on Computer systems
• Increased CPU speed. High-speed network and different storage attachments.
• Virtualization allowed a single server to support multiple operating systems.

Threads

• Multiple actions executing simultaneously.
• Heavyweight processes known as (conventional processes) own the resources and are a passive element.
• Lightweight process (thread) uses a CPU, scheduled for execution, is as an active element.
• Multithreaded applications programs contains threads running at a given time and have examples like internet browsers.

Object-Oriented Design

• Drives system architecture improvements.
• Kernel (operating system nucleus) resides in memory, performs essential tasks, is protected by hardware
• Modules for process scheduling/memory allocation, & other functions memory resident.
• Modification and customization are easier because integrity of the system is assured when software development is becoming productive.

Explore the fundamental concepts and functions of operating systems. Understand their evolution, roles, and management of hardware and software. Learn about different types of operating systems and the impact of multiprocessing and virtualization.