JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2021 OPERATING SYSTEMS Previous Question Paper (February - 2021 - R17)

An operating system provides an environment for the execution of programs and offers a variety of services to both users and system processes. These services are designed to make the programming task easier and to ensure efficient system operation.

The primary services include:

• Program Execution: The system must be able to load a program into memory and run it. The OS handles the allocation of resources and the termination of the process, whether normal or abnormal.
• I/O Operations: Since user programs cannot directly access I/O devices, the OS provides a uniform interface to handle device-specific drivers, buffering, and caching to manage input and output operations efficiently.
• File System Manipulation: The OS manages the creation, deletion, reading, writing, and searching of files and directories. It also enforces permissions to control access to these files.
• Communications: Processes often need to exchange information. This can occur between processes on the same computer via shared memory or message passing, or between processes on different computer systems via a network.
• Error Detection: The OS constantly monitors the system for potential errors in the CPU, memory, I/O devices, or user programs. It takes appropriate action to ensure consistent and correct computing.
• Resource Allocation: When multiple users or jobs run concurrently, the OS must allocate resources such as CPU cycles, main memory, and file storage to each process to ensure optimal system performance.
• Accounting: The OS keeps track of which users use how much and what kinds of computer resources. This data is useful for performance tuning and billing purposes.
• Protection and Security: The OS ensures that all access to system resources is controlled. Protection involves ensuring that all access to system resources is controlled, while security involves defending the system against internal and external threats like unauthorized access or malware.