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Operatins Systems
Computer Science
Undergraduate 3

Additional Computer Science Flashcards





Efficiency and functionality are key to an operating system’s usefulness.

Efficiency sets the stage for the performance of all software on a computer.

  Application software is intended to solve a specific problem or to provide generic tools for end users.

Ex. Inventory control application software uses the computer to track & report a company's inventory.




What is systems software? provides a general programming environment where programmers create specific applications to suit customers' needs. The environment is made up of programming tools such as editors & compilers & abstractions like files & objects. System software & hardware exist to support the creation & effective use of application software. Operating System is the part of the system software that manages the use of the hardware by other system software and all application software. OS is the software that is implemented "closest to the hardware"

System supports concurrent execution or concurrency when either it appears that two or more programs are being executed or they are executing at the same time. If there are true simultaneous operations, then it’ll be called parallel or simultaneous execution between two programs. Concurrent & parallel exe are related to the notion ofresource sharing: for executing programs to be concurrent or parallel, they must share the computer. 



An OS manages some of the resources by transparently sharing among the abstract machines.  Users & application programmers are unaware that resources are being shared. An OS also allows explicit sharing among executing programs by providing mechanisms by which the application programmers manage the way the machine's resources are to be shared.

*Exclusive use of resources

* Batch Systems—handle collections, or batches, of jobs. A job is predefined sequence of commands (“compile a program” or “execute a program”), programs and data. Batch processing systems were the first to use multiprogramming. This allowed the OS to execute a few jobs but not the entire batch concurrently.




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*Timesharing systems—support multiple interactive users. Rather than the user preparing a job for execution ahead of time, user establishes an interactive session with the computer & then provides commands, programs, and data, as they are needed during the session. These systems stimulated development of more sophisticated multiprogramming mechanisms than were used in batch systems. TS also drove the need for the OS to provide timely response for users & sharpened the focus on resource management & protection mechanisms.

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