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An operating system should be conceived as a combination of following different aspects:-
1. A Programbut with a funny function invocation mechanism. An operating system is no different than any other program, other than it lays on the bottommost layer.
2. A Control Programcontrols the execution of programs and devices. An operating sytem is responsible to monitor and control the operation of each and every software as well as hardware components of a computer system.
3. An Interface An abstract virtual machine. Operating system behaves as a computer system for all other applications so that the communication is possible and the underlying hardware details are encapsulated to provide common standard interface.
4. A Programming Environment The kernel + utilities
5. A resource manager The operating system maximizes system performance since it manages the available resources.
6. A service provider An operating system provides different services to other applications such as File storage, network communications, and so on.Why do we need operating system?Today it would appear a funny question.
We can't imagine operating a computer without an operating system. But, major reason can be drawn as following two:-
1. They Provide a high-level abstraction of physical resources Since operating systems provice common standard interface, it enables the construction of more complex software systems. Similarly, without operating system, it would be impossible to imagine portable code.
2. They allow sharing of limited or expensive physical resources Because operating systems manages the computer resources it is possible to share the expensive physical resources and optimize their use.
A Brief History of Operating Systems Hand Programmed Machines ('45-'55) Single Usser SystemsOS = loader + libraries of common subroutines Drawback: low utilization of expensive components Batch Processing or Offline processing ('55-'65) Pipelined processing of jobs. (Overlap computation with I/O)Utilization is higher But throughput is low. [throughput=(number of jobs completed)/(observation interval)Operating System = loader + sequencer + output processor Spooling Processing or online processing ('62-'69)Disks/drums enabled overlap of I/O and computation on the same machine Utilization is higher And at the same time throughput too improved Multiprogramming ('65-'80) Keeps several jobs in memory and multiplex CPU between job Simple, synchronous input. This solved the problem of 'what to do while waiting for the I/O device?' Timesharing('70- A timer interrupt is used to multiplex CPU among job
Types of Operating Systems
Personal Computing System
Single user
Utilization is no longer a concern
Emphasis is on user interface and API
Many serices and features are not present
Primary concern in personal computing system is response time [ response time = completion time - start time]Distributed Operating System Typically support distributed services Possibly employ multiple processors (loosely coupled vs. tightly coupled systems) High availability and reliability requirementParallel Operating System Symetric Multiprocessing Each processor has a copy of the operating system. Many jobs can be executed in parallel Asymmetric multiprocessingMaster processor allocates jobs to slave processors
Real-time Operating System A system with a dual notion of correctnesLogical correctness - "It does the right thing"Temporal correctness - "It does it on time A system wherein predictability is more important than performance Dedicated system: real-time performance achieved iff time(loop)<= 33ms. Realtime computing is a programming problem ("Just buy a faster processor") Multiprogrammed system: real-time performance iff ??? Real time computing is an operating system problem.OS Concepts is a Research and Management consulting firm with specialties In Project Management, Information Communication and Technology (ICT) and corporate solution development and deployment. Our services include scheduled and on-demand training in the areas of project management, Business Analysis, Process improvement, Risk Management, Total Quality Management (TQM), Change management and Microsoft Project. We have partners both in the UK and India.OS Concepts is a Research and Management consulting firm with specialties In Project Management, Information Communication and Technology (ICT) and corporate solution development and deployment. Our services include scheduled and on-demand training in the areas of project management, Business Analysis, Process improvement, Risk Management, Total Quality Management (TQM), Change management and Microsoft Project. We have partners both in the UK and India.Vision Statement To equip people with skills and provide a platform for them to explore their God given potentials To liberate our society from the shackles of ignorance, corruption and poverty by mining the ‘gold’ in people’s minds.To bridge the gap between the theoretical and the practical, thereby uplifting Nigeria.To bridge the Digital, Skill and Competency divide between the Global South and North (the Developing nations and Developed nations of the world).Mission Statement
To deal with our clients with honestly and openness
To use Information Technology as a leverage in delivering values to our clients
To treat our clients with uttermost respect and care
To deliver and develop exceptional services and products consistently
Our Core Strength OS Concepts' core strengths include:
Exceptional Customer Service
Quality of Services
Professional Experience
Competitive Pricing
Innovation and Resourcefulness
Global Network
1. A Programbut with a funny function invocation mechanism. An operating system is no different than any other program, other than it lays on the bottommost layer.
2. A Control Programcontrols the execution of programs and devices. An operating sytem is responsible to monitor and control the operation of each and every software as well as hardware components of a computer system.
3. An Interface An abstract virtual machine. Operating system behaves as a computer system for all other applications so that the communication is possible and the underlying hardware details are encapsulated to provide common standard interface.
4. A Programming Environment The kernel + utilities
5. A resource manager The operating system maximizes system performance since it manages the available resources.
6. A service provider An operating system provides different services to other applications such as File storage, network communications, and so on.Why do we need operating system?Today it would appear a funny question.
We can't imagine operating a computer without an operating system. But, major reason can be drawn as following two:-
1. They Provide a high-level abstraction of physical resources Since operating systems provice common standard interface, it enables the construction of more complex software systems. Similarly, without operating system, it would be impossible to imagine portable code.
2. They allow sharing of limited or expensive physical resources Because operating systems manages the computer resources it is possible to share the expensive physical resources and optimize their use.
A Brief History of Operating Systems Hand Programmed Machines ('45-'55) Single Usser SystemsOS = loader + libraries of common subroutines Drawback: low utilization of expensive components Batch Processing or Offline processing ('55-'65) Pipelined processing of jobs. (Overlap computation with I/O)Utilization is higher But throughput is low. [throughput=(number of jobs completed)/(observation interval)Operating System = loader + sequencer + output processor Spooling Processing or online processing ('62-'69)Disks/drums enabled overlap of I/O and computation on the same machine Utilization is higher And at the same time throughput too improved Multiprogramming ('65-'80) Keeps several jobs in memory and multiplex CPU between job Simple, synchronous input. This solved the problem of 'what to do while waiting for the I/O device?' Timesharing('70- A timer interrupt is used to multiplex CPU among job
Types of Operating Systems
Personal Computing System
Single user
Utilization is no longer a concern
Emphasis is on user interface and API
Many serices and features are not present
Primary concern in personal computing system is response time [ response time = completion time - start time]Distributed Operating System Typically support distributed services Possibly employ multiple processors (loosely coupled vs. tightly coupled systems) High availability and reliability requirementParallel Operating System Symetric Multiprocessing Each processor has a copy of the operating system. Many jobs can be executed in parallel Asymmetric multiprocessingMaster processor allocates jobs to slave processors
Real-time Operating System A system with a dual notion of correctnesLogical correctness - "It does the right thing"Temporal correctness - "It does it on time A system wherein predictability is more important than performance Dedicated system: real-time performance achieved iff time(loop)<= 33ms. Realtime computing is a programming problem ("Just buy a faster processor") Multiprogrammed system: real-time performance iff ??? Real time computing is an operating system problem.OS Concepts is a Research and Management consulting firm with specialties In Project Management, Information Communication and Technology (ICT) and corporate solution development and deployment. Our services include scheduled and on-demand training in the areas of project management, Business Analysis, Process improvement, Risk Management, Total Quality Management (TQM), Change management and Microsoft Project. We have partners both in the UK and India.OS Concepts is a Research and Management consulting firm with specialties In Project Management, Information Communication and Technology (ICT) and corporate solution development and deployment. Our services include scheduled and on-demand training in the areas of project management, Business Analysis, Process improvement, Risk Management, Total Quality Management (TQM), Change management and Microsoft Project. We have partners both in the UK and India.Vision Statement To equip people with skills and provide a platform for them to explore their God given potentials To liberate our society from the shackles of ignorance, corruption and poverty by mining the ‘gold’ in people’s minds.To bridge the gap between the theoretical and the practical, thereby uplifting Nigeria.To bridge the Digital, Skill and Competency divide between the Global South and North (the Developing nations and Developed nations of the world).Mission Statement
To deal with our clients with honestly and openness
To use Information Technology as a leverage in delivering values to our clients
To treat our clients with uttermost respect and care
To deliver and develop exceptional services and products consistently
Our Core Strength OS Concepts' core strengths include:
Exceptional Customer Service
Quality of Services
Professional Experience
Competitive Pricing
Innovation and Resourcefulness
Global Network
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