Operating System Operations & Services it provides

•  Operating System Operations :

1. 1.  Multi programming and multitasking 

2. 2.  Timer maintenance 

3. 3.  Resource Management 

   1. a)  Process Management 

   2. b)  Memory management 

   3. c)  Input/Output Management 

   4. d)  Mass storage Management 

   5. e)  Cache Memory Management 

   6. f)  File System Management 

4. 4.  Security and Protection 

5. 5.  Virtualization 

* OS provide services in following areas :

1.  Program Development :

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• The OS provides a variety of facilities and services, such as  editors and debuggers, to assist the programmer in creating programs. 
• Typically, these services are in the form of utility programs that, while not strictly part of the core of the OS, are supplied with the OS and are referred to as application program development tools. 

2.  Program Execution :

• A number of steps need to be performed to execute a program. 
• Instructions and data must be loaded into main memory, I/O devices and files must be initialized, and other resources must be prepared.  
• The OS handles these scheduling duties for the user. 

 

3.  Access to I/O Devices :

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• Each I/O device requires its own peculiar set of instructions or control signals for operation. 
• The OS provides a uniform interface that hides these details so that programmers can access such devices using simple reads and writes. 

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4.  Controlled File Access :

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• For file access, the OS must reflect a detailed understanding of not only the nature of the I/O device (disk drive, tape drive) but also the structure of the data contained in the files on the storage medium. 
•  In the case of a system with multiple users, the OS may provide protection mechanisms to control access to the files. 

 

6. 5.  System Access :

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• Error detection and response: A variety of errors can occur while a computer system is running. 
• These include internal and external hardware errors, such as a memory error, or a device failure or malfunction; and various software errors, such as division by zero, attempt to access forbidden memory location, and inability of the OS to grant the request of an application. 

 

6. 6.  Accounting :

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• A good OS will collect usage statistics for various resources and monitor performance parameters such as response time.  
• On any system, this information is useful in anticipating the need for future enhancements and in tuning the system to improve performance. 

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8. 7.  Instruction Set Architecture (ISA) :

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• The ISA defines the range/list of machine language instructions that a computer can follow.  
• It is a boundary between hardware and software. 
• Application programs and utilities may access the a subset of ISA directly. 
• The OS has access to additional machine language instructions that deal with managing system resources (system ISA). 

 

8. 8.  Application Binary Interface :

• The ABI defines a standard for binary portability across programs. 

• The ABI defines the system call interface to the operating system and the hardware resources and services available in a system through the user ISA. 

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9.  Application Programming Interface :

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• The API gives a program access to the hardware resources and services available in a system through the user ISA supplemented with high-level language (HLL) library calls. 
• Any system calls are usually performed through libraries.  
• Using an API enables application software to be ported easily, through recompilation, to other systems that support the same API.