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Computer Science 101

Computer Science 101. The Virtual Machine: Operating Systems. From Hardware to Software. Naked machine Hardware bereft of any helpful user-oriented features Data as well as instructions must be represented in binary To make a Von Neumann computer usable:

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Computer Science 101

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  1. Computer Science 101 The Virtual Machine: Operating Systems

  2. From Hardware to Software • Naked machine • Hardware bereft of any helpful user-oriented features • Data as well as instructions must be represented in binary • To make a Von Neumann computer usable: • Create an interface or virtual machine between the user and the hardware

  3. From Hardware to Software • The virtual machine • System software:collection of computer programs that manage the resources of a computer and facilitate access to those resources • Software: sequences of instructions that solve a problem

  4. Types of System Software

  5. Types of System Software • Operating system • Communicates with users • Determines what they want • Activates other system programs, applications packages, or user programs to carry out their request

  6. Some Typical OS Commands

  7. Terminal-based user interface (prompt and keyboard input of commands)

  8. OS Responsibilities • Major responsibilities of operating systems • User interface management (a receptionist) • Control of access to system and files (a security guard) • Program scheduling and activation (a dispatcher) • Efficient resource allocation (an efficiency expert) • Deadlock detection and error detection (a traffic officer)

  9. History of Operating Systems • First-generationsystem software • Roughly 1945–1955 • No operating systems and very little software support • Second-generationsystem software • Called batch operating systems (1955–1965) • Command language • Commands specifying to the operating system what operations to perform on programs

  10. Batch Processing

  11. Time Sharing Operating Systems • Third-generation operating systems • Multiprogrammed operating systems(1965–1985) • Many programs can be stored in memory • Allows programmer to enter system commands, programs, and data online • Allows multiple programmers to run programs simultaneously on one computer (time sharing)

  12. A Time-Sharing System

  13. Network Operating System • Much of the computing was done remotely in the office, laboratory, classroom, and factory • Fourth-generationoperating system (1985–present)

  14. The Future • Multimedia user interfaces • Will interact with users and solicit requests in a variety of ways • Parallel processing operating system • Can efficiently manage computer systems containing tens, hundreds, or even thousands of processors • Distributed computing environment • Users do not need to know the location of a given resource within the network

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