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23 Cards in this Set
- Front
- Back
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List the Operating System Service (Functions that are helpful to user)
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User Interface
Program Execution I/O operations File-Systems Communications Error Detection |
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List the Operating System Service (ensuring efficent operation of the system)
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Resource Allocation
Accounting Protection Security |
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User Interface Forms
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CLI
GUI Batch |
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Program Execution
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x
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I/O operations Examples
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Outputting to a display, reading from a DVD player.
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File-system manipulation
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x
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Communications
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x
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Error detection
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OS needs to be constantly aware of possible errors
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Resource allocation
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x
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AccountingProtection and security
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The owners of information stored in a multiuser or networked computer system may want to control use of that information. Process should not interfere with others when several separate processes execute concurrently.
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Protection
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Protection involves ensuring that all access to system resources is controlled.
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Security
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Security of the system from outsiders requires user authentication, extends to defending external I/O devices from invalid access attempts.
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Command Line Interface
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Command Line Interface (CLI) or command interpreter allows users to directly enter commands
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Main function of the command interpreter
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Get and execute the next user-specified command
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How are CLI commands typically implimented
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As system programs, for example "ls" is a program
Example: UNIX command to delete file rm file.txt |
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Programmer can add new commands to the system by creating new files, show an example
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zip utility
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System Calls
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Provide an interface to the services made available by OS
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Application Programming Interface (API)
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API specifies a set of functions that are available to an application programmer, including the parameters that are passed to each function and the return values
That is, program via a high-level API rather than direct system call |
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Three most common APIs are:
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Win32 API for Windows systems,
POSIX API for POSIX-based systems (including virtually all versions of UNIX, Linux, and Mac OS X), and Java API for the Java virtual machine (JVM) |
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What does an API function Typically do?
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The function that make up an API typically invoke the actual system calls on behalf of the application programmer
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Why use APIs rather than system calls?
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API abstracts the system calls. Making it easier to implement.
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System-call interface
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System-call interface maintains a table indexed according to these numbers
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Types of System Calls
Can be grouped into five major categories: |
Process control
File management Device management Information maintenance Communications |
