Operating System Interview Questions and Answers

Answer - 1 : - Operating systems exist for two main purposes. One is that it is designed to make sure a computer system performs well by managing its computational activities. Another is that it provides an environment for the development and execution of programs.

Answer - 2 : - The procedure of starting a computer by loading the kernel is known as booting the system. When a user first turn on or booted the computer, it needs some initial program to run. This initial program is known as Bootstrap Program. It is stored in read-only memory (ROM) or electrically erasable programmable read-only memory (EEPROM). Bootstrap program locates the kernel and loads it into main memory and starts its execution.

Answer - 3 : - Main memory is also called random access memory (RAM). CPU can access Main memory directly. Data access from main memory is much faster than Secondary memory. It is implemented in a semiconductor technology, called dynamic random-access memory (DRAM). Main memory is usually too small to store all needed programs. It is a volatile storage device that loses its contents when power is turned off. Secondary memory can stores large amount of data and programs permanently. Magnetic disk is the most common secondary storage device. If a user wants to execute any program it should come from secondary memory to main memory because CPU can access main memory directly.

Answer - 4 : - Systems which have more than one processor are called multiprocessor system. These systems are also known as parallel systems or tightly coupled systems. Multiprocessor systems have the following advantages. - Increased Throughput: Multiprocessor systems have better performance than single processor systems. It has shorter response time and higher throughput. User gets more work in less time. - Reduced Cost: Multiprocessor systems can cost less than equivalent multiple single processor systems. They can share resources such as memory, peripherals etc. - Increased reliability: Multiprocessor systems have more than one processor, so if one processor fails, complete system will not stop. In these systems, functions are divided among the different processors.

Answer - 5 : - Deadlock with one process is not possible. Here is the explanation. A deadlock situation can arise if the following four conditions hold simultaneously in a system. - Mutual Exclusion. - Hold and Wait. - No Preemption. - Circular-wait. It is not possible to have circular wait with only one process, thus failing a necessary condition for Circular wait. There is no second process to form a circle with the first one. So it is not possible to have a deadlock involving only one process.

Answer - 6 : - An operating system is a collection of software programs which control the allocation and usage of various hardware resources in the system. It is the first program to be loaded in the computer and it runs in the memory till the system is shut down. Some of the popular Operating Systems are DOS, Windows, Ubuntu, Solaris etc.

Answer - 7 : - The main functions of an OS are: a. Process Management b. Memory Management c. Input/ Output Management d. Storage/ File system management

Answer - 8 : - - Kernel is the part of OS which handles all details of sharing resources and device handling. - It can be considered as the core of OS which manages the core features of an OS. - Its purpose is to handle the communication between software and hardware - Its services are used through system calls. - A layer of software called shell wraps around the Kernel.

Answer - 9 : - The main functions of a Kernel are: - Process management - Device management - Memory management - Interrupt handling - I/O communication - File system management

Answer - 10 : - Kernels are basically of two types: a. Monolithic Kernels - In this architecture of kernel, all the system services were packaged into a single system module which lead to poor maintainability and huge size of kernel. b. Microkernels - They follow the modular approach of architecture. Maintainability became easier with this model as only the concerned module is to be altered and loaded for every function. This model also keeps a tab on the ever growing code size of the kernel.