Operating system technical interview questions and answers help students and job seekers understand core computing concepts that are essential for technical interviews. The operating system acts as a bridge between hardware and software, making it one of the fundamental subjects tested in campus placement interviews. Recruiters frequently ask questions about process management, memory allocation, deadlocks, scheduling algorithms, threads, file systems, and OS architecture. These OS interview questions appear repeatedly in companies like TCS, Wipro, Infosys, Cognizant, Capgemini, and Accenture. This guide explains the most commonly asked OS interview questions with easy-to-understand answers, practical examples, and simple definitions. Whether you are preparing for your first job, a technical round, or a written placement test, understanding OS concepts will help you perform confidently. You can also practice mock questions or download PDFs to strengthen your preparation.
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101. What are the basic functions of an operating system?
Operating system controls and coordinates the use of the hardware among the various applications programs for various uses. Operating system acts as resource allocator and manager. Since there are many possibly conflicting requests for resources the operating system must decide which requests are allocated resources to operating the computer system efficiently and fairly. Also operating system is control program which controls the user programs to prevent errors and improper use of the computer.
102. Explain briefly about, processor, assembler, compiler, loader, linker and the functions executed by them.
Processor:A processor is the part a computer system that executes instructions .It is also called a CPU
Assembler: — An assembler is a program that takes basic computer instructions and converts them into a pattern of bits that the computers processor can use to perform its basic operations. Some people call these instructions assembler language and others use the term assembly language.
Compiler: — A compiler is a special program that processes statements written in a particular programming
103. What is a Real-Time System?
A real time process is a process that must respond to the events within a certain time period. A real time operating system is an operating system that can run real time processes successfully
104. What is the difference between Hard and Soft real-time systems?
A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. A soft real time system where a critical real-time task gets priority over other tasks and retains that priority until it completes. As in hard real time systems kernel delays need to be bounded
105. What is virtual memory?
A virtual memory is hardware technique where the system appears to have more memory that it actually does. This is done by time-sharing, the physical memory and storage parts of the memory one disk when they are not actively being used
106. What is cache memory?
Cache memory is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data
107. Differentiate between Complier and Interpreter?
An interpreter reads one instruction at a time and carries out the actions implied by that instruction. It does not perform any translation. But a compiler translates the entire instructions.
108. What are different tasks of Lexical Analysis?
The purpose of the lexical analyzer is to partition the input text, delivering a sequence of comments and basic symbols. Comments are character sequences to be ignored, while basic symbols are character sequences that correspond to terminal symbols of the grammar defining the phrase structure of the input
109. Why paging is used?
Paging is solution to external fragmentation problem which is to permit the logical address space of a process to be noncontiguous, thus allowing a process to be allocating physical memory wherever the latter is available.
110. What is Context Switch?
Switching the CPU to another process requires saving the state of the old process and loading the saved state for the new process. This task is known as a context switch.Context-switch time is pure overhead, because the system does no useful work while switching. Its speed varies from machine to machine, depending on the memory speed, the number of registers which must be copied, the existed of special instructions(such as a single instruction to load or store all registers).