CS2411 – OPEARATING SYSTEMS

1.What is an operating system?

An operating system is a program that manages the computer hardware. it act as an intermediate between a users of a computer and the computer hardware. It controls and coordinates the use of the hardware among the various application programs for the various users.

2.What is the kernel?

A more common definition is that the OS is the one program running at all times on the computer ,usually called the kernel, with all else being application programs.

3.What are batch systems?

Batch systems are quite appropriate for executing large jobs that need little interaction. The user can submit jobs and return later for the results. It is not necessary to wait while the job is processed.

4.What is graceful degradation?

In multiprocessor systems, failure of one processor will not halt the system, but only slow it down by sharing the work of failure system by other systems. This ability to continue providing service is proportional to the surviving hardware is called graceful degradation.

5.Differentiate Tightly coupled systems and loosely coupled systems?

Loosely coupled systems Tightly coupled systems Each processor has its own local memory Common memory is shared by many processors Each processor can communicate with other all through communication lines No need of any special communication lines

6.What is real time system?

A real time system has well defined ,fixed time constraints. Processing must be done within the defined constraints, or the system will fail. It is often used as a control device in a dedicated application.

7.What are privileged instructions?

Some of the machine instructions that may cause harm to a system are designated as privileged instructions. The hardware allows the privileged instructions to be executed only in monitor mode.

8.What do you mean by system calls?

System calls provide the interface between a process and the operating system. When a system call is executed, it is treated as by the hardware as software interrupt.

9.What is a process?

A process is a program in execution. It is an active entity and it includes the process stack,containing temporary data and the data section contains global variables.

 

10.What is process control block?

Each process is represented in the OS by a process control block. It contain many pieces of information associated with a specific process.