Operating system concepts
- 1. Operating System Concepts Prof Neeraj Bhargava Vaibhav Khanna Department of Computer Science School of Engineering and Systems Sciences Maharishi Dayanand Saraswati University Ajmer
- 2. Computer System Structure • Computer system can be divided into four components: – Hardware – provides basic computing resources • CPU, memory, I/O devices – Operating system • Controls and coordinates use of hardware among various applications and users – Application programs – define the ways in which the system resources are used to solve the computing problems of the users • Word processors, compilers, web browsers, database systems, video games – Users • People, machines, other computers
- 3. Abstract View of Components of Computer
- 4. What Operating Systems Do • Depends on the point of view • Users want convenience, ease of use and good performance – Don’t care about resource utilization • But shared computer such as mainframe or minicomputer must keep all users happy – Operating system is a resource allocator and control program making efficient use of HW and managing execution of user programs • Users of dedicate systems such as workstations have dedicated resources but frequently use shared resources from servers • Mobile devices like smartphones and tables are resource poor, optimized for usability and battery life – Mobile user interfaces such as touch screens, voice recognition • Some computers have little or no user interface, such as embedded computers in devices and automobiles – Run primarily without user intervention
- 5. Defining Operating Systems • Term OS covers many roles – Because of myriad designs and uses of OSes – Present in toasters through ships, spacecraft, game machines, TVs and industrial control systems – Born when fixed use computers for military became more general purpose and needed resource management and program control
- 6. Operating System Definition (Cont.) • No universally accepted definition • “Everything a vendor ships when you order an operating system” is a good approximation – But varies wildly • “The one program running at all times on the computer” is the kernel, part of the operating system • Everything else is either – a system program (ships with the operating system, but not part of the kernel) , or – an application program, all programs not associated with the operating system • Today’s OSes for general purpose and mobile computing also include middleware – a set of software frameworks that provide addition services to application developers such as databases, multimedia, graphics
- 7. OS as an Extended Machine • An operating system is the most important program in a computer system. This is one program that runs all the time, as long as the computer is operational and exits only when the computer is shut down. • The fundamental goal of computer systems is to execute user programs and to make solving user problems easier. Hardware of a computer is equipped with extremely capable resources – memory, CPU, I/O devices etc. • All these hardware units interact with each other in a well-defined manner. Also various programs require certain common operations, such as those controlling the I/O devices. • The common functions of controlling and allocating resources are then brought together into one piece of software: the operating system.
- 8. • Operating systems exist because they are supposed to make it easier to compute with them than without them. • Efficient operation of the computer system is a secondary goal of an operating system. This goal is particularly important for large, shared multi- user systems. • Operating systems are the programs that make computers operational, hence the name Operating (the )system.
- 9. Operating System as an Extended Machine