Operating System

The operating system is referred to as a group of applications that manages every aspect of a computer's operation, including recognizing keyboard input, providing output to the screen, keeping track of files and directories on the disk, and managing peripheral devices like disk drives and printers. It serves as the interface between computer systems' users and their associated hardware and application software. When a computer is turned on, it is the first program that runs, and it is the last program that runs when the machine is shut off. An operating system's function is to offer a setting in which a user can conveniently and effectively run programs. No computer can work without an operating system.

A computer operating system's two main goals are:

• Making a computer system user-friendly.
• Using a computer system's resources.

Functions of an operating system

Every operating system carries out a few fundamental tasks, such as the ones listed below:

• Process management:
  • A running or executing application is referred to as a process. In a multi-tasking environment, the operating system must make sure that each running program (process) is given an equitable share of processing time. The processor is effectively and maximally used. The operating system determines the processor and process state, selects the job and processes inside it, allots the processor to the process, and releases the processor once the process has finished.
• Input and output management:
  • The numerous input and output devices are controlled, safeguarded, and regulated by the input and output management module. From a programmer's perspective, the operating system merely renders all input and output devices as well as hardware independent. The management of input and output devices by the operating system improves the efficiency of input and output. The operating system receives input from the input device, stores it in main memory, requests processing from the CPU, and then sends the processed data to the output devices for output.
• Security:
  • The operating system is also in charge of security, making sure that data is protected from exposure and corruption, kept private, and that unauthorized users are kept out of the system. The operating system ensures that only permitted users have access to the machine and its data and that those users only carry out their permitted tasks.
• Command interpreter:
  • One component of the operating system called a command interpreter reads the commands that users write into a terminal, interprets them, and then translates them into specific instructions that the computer hardware may follow. From one operating system to the next, it differs significantly. Each operating system needs to have a command interpreter to function.
• Memory management:
  • As soon as they were processed, it used to handle live or active data. Particularly in systems with many processors, the operating system must handle four areas of demand. They are protection, sharing, logical organization, relocation (when changes take place in the area of memory allotted to a process), and relocation. The extensive collection of words or bytes in memory, each having a unique address. The operating system determines the amount of memory needed for the program instructions and data when a user requests a read/write operation on the CPU. In order to load the program and data into RAM, the operating system then allots the necessary memory. When a program exits, its memory space is freed, and another program is given access to it.
• Time sharing:
  • CPU time is managed by the operating system. The kernel operating system periodically checks for requests for CPU time from other programs. Every 10 milliseconds, time sharing checks for CPU requests from higher priority activities. CPU time is divided into segments, specified by time slice, and distributed across programs in a round-robin method when two or more processes with the same priority level are vying for CPU time. This prevents one process from controlling the CPU until it blocks or terminates.
• Deadlock prevention:
  • A situation where a resource shared by two or more processes cannot continue because the resource needed by one process is held by the other can occur during processing. We refer to this circumstance as a standstill. By carefully distributing resources, the operating system makes sure that the aforementioned condition is not true.
• Interrupt handling:
  • A device or application will send out an interrupt signal when they require the CPU's attention. The operating system chooses the interrupt's type and priority, halts the CPU's execution, maintains the CPU's original state, does the requested operation, and returns the CPU to its starting state.
• Virtual storage:
  • Virtual memory is the reserved space in the secondary memory that the operating system uses when a program's size exceeds the computer's main memory (RAM). Although it enables the execution of larger programs (than ram), the process also slows down.

Reference

Ghishing, Er.Ashim. Computer Science. Kathmandu, Nepal: Benchmark , 2008.