General Operating Systems Interview questions

Q1. Explain paging in OS.

Ans. External fragmentation problem in OS is solved through paging which permits the logical address space of a process to be noncontiguous and allowing a process to be allocating physical memory.


Ans. An Operating System is a software program that enables the computer hardware to communicate and operate with the computer system.

Q3. Define virtual memory.

Ans. Virtual memory is hardware technique in which the system appears to have more memory that it actually does. This is done by time-sharing.

Q4. Explain Hard real time systems?

Ans. A hard real time system guaranties the completion of critical tasks on time. This approach requires that all delays in the system needs to be bounded from the retrieval of the stored data to the time that it takes the operating system ( OS ) to complete any request.

Q5. Define cache memory?

Ans. Cache memory is part of random access memory (RAM) that a computer microprocessor can access more quickly. As the microprocessor processes data, it looks first in the cache memory, it does not have to do the more time-consuming reading of data from larger memory. It can be toggle chip.

Q6. Explain Soft real time systems?

Ans. A soft real time system where there is 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.

Q7. What are the different types of memory?

Ans. The following are the memory types:

DIMM – Dual-Line Memory Modules: Used to store two rows of chips which are soldered onto printed circuit board and enables to contain two times memory than SIMM

SDRAM – Static RAM – Holds data and refreshing does not required. It is faster than DRAM.

DRAM – Dynamic Random Access Memory: It holds data for short time period and will be refreshed periodically.\ SIMM – Single-Line Memory Modules: Used to store single row of chips which are soldered onto Printed Circuit Board.

Shadow RAM: Allows the moving of selected parts of BIOS code that is available in ROM to the faster RAM.

Flash Memory: A non volatile, rewritable and solid state memory which performs the functions of both RAM and hard disk combined. Data is retained in the memory, in case of power loss. It is ideal for printers, cellular phones, digital cameras, pagers.

Q8. Define Dirty bit? What is the role of dirty bit?

Ans. A bit in a memory cache or virtual memory page which has been modified by the CPU. So the possiblity of miss match is increased in Dirty bit

 Q9. What is the full form of “windows xp “

Ans. It has the full fom of windows experience.

 Q10. Differentiate between NTFS and FAT32?

Ans.  FAT (FAT16 and FAT32) and NTFS are the methods used for storing data on a hard drive. The hard drive has to either be formatted using one to the other (usually FAT to NTFS) using a system tool.

It also supports large volumes of data and powerful storage such as RAID. The most important feature of NTFS is the ability to encrypt files and folders to protect our sensitive data

 Q11. Define Safe State and its use in deadlock avoidance?

Ans. When a request is made by process for an available resource, system must decide if immediate allocation will leave the system in a safe state. System is in safe state if there lies a safe sequence of all processes. Deadlock Avoidance ensures that a system will never enter an unsafe state.

 Q12. Differentiate between Unix and windows?

Ans.  Unix is very flexible and avails more than one ways to do the same thing. In windows its the MS way.Windows has a large user-base and has control over desktop and home PCs due to its good looking easy to use interface whereas the server market is still under Unix / Linux control because it offers more clearer view of internal details of what is actually going through the system. Windows also offers integration (everything in one place) but this adds extra complexity whereas Unix follows the keep it small keep it simple terminology.

 Q13. Define exchange server?

Ans. Exchange server is a microsoft product and is used for mail server. With microsoft server it uses other server facility and AD Users.

 Q14. Explain DHCP and its working?

Ans. DHCP means Dynamic Host Configuration Protocol. It works only in server client mode as it assigns addressing information to client thus Client asks addressing information from DHCP Server by four way communication.

 Q15. What will happen if interrupt signals arrive at the same time to the processor?

Ans. Interrupt signals are handled based on priority. There are basically two modes of execution. Privilege mode and user mode. In Privilege mode only the privilege instructions gets executed.

 Q16. Is the OS is the part of Architecture or it is the part of Organization ?

Ans. Yes, it is a part of Architecture. 

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