Ans: Operating systems exist for:

• Easeness to use
• Efficient computational resource management
• Providing environment for the development and execution of programs.

Ans:Demand paging is a type of swapping in virtual memory management system in which pages of data are not copied from disk to RAM until they are needed.

Ans:When multiple programs reside in memory and executed in time sharing manner, this type of systems are called multi-programming systems.

Ans:More than one processors interconnected to each other are placed within a system to work as a single unit of system. This type of systems are called multiprocessor systems.

Ans:With an increased number of processors, there is considerable increase in throughput. It can also save more money because they can share resources. Finally, overall reliability is increased
as well.

Ans:Kernel is the program always in running state, which implements core functionalities of operating system. It connects applications to the actual processing of data. It also manages all communications between software and hardware components to ensure usability and reliability.

Ans:When time plays an important role in happening of events real-time systems comes into picture. Real-time systems are used when rigid time requirements have been placed on the operation of a processor. It has well defined and fixed time constraints.

Ans:Virtual memory is a memory management technique for letting processes execute outside of memory. This is very useful especially when an executing program cannot fit in the physical memory. (When size of a program is greater than available memory of system, with the help of virtual memory concept, only a part of the program is loaded into main memory and rest is stored in secondary storage and bring into memory when need.

Ans:The main objective of multi-programming is to have process running at all times. With this design, CPU utilization is said to be maximized.

Ans:In a Time sharing system, the CPU executes multiple jobs by switching among them, also known as multitasking. This process happens so fast that users can actually interact with each program while it is running.

Ans:In this system, each processor runs an identical copy of the operating system, and these copies communicate with one another as needed.

Ans:Server systems can be classified as either computer-server systems or file server systems. In the first case, an interface is made available for clients to send requests to perform an action. In the second case, provisions are available for clients to create, access and update files.