operating System Questions

Give the difference between multiprogramming and multiprocessing.              

Ans:

A multiprocessing  system is a computer hardware configuration that includes more

than one independent processing unit. The term multiprocessing is generally used to refer to large computer hardware complexes found in major scientific or commercial applications.   The   multiprocessor   system   is   characterized   by-increased   system throughput and application speedup-parallel processing. The main feature of this architecture is to provide high speed at low cost in comparison to uni- processor.

A multiprogramming  operating system is system that allows more than one active user program (or part of user program) to be stored in main memory simultaneously. Multi programmed operating systems are fairly sophisticated. All the jobs that enter the system are kept in the job pool. This pool consists of all processes residing on mass storage awaiting allocation of main memory. If several jobs are ready to be brought into memory,  and there is not enough  room for all of them, then the system  must choose among them. A time-sharing system is a multiprogramming system.

Write down different system calls for performing different kinds of tasks.            

Ans:

A  system  call  is  a  request  made  by  any  program  to  the  operating  system  for

performing tasks -- picked from a predefined set -- which the said program does not have  required  permissions  to  execute  in  its  own  flow  of  execution.  System  calls provide the interface between a process and the operating system. Most operations interacting with the system require permissions not available to a user level process, e.g. I/O performed with a device present on the system or any form of communication with other processes requires the use of system calls.

The main types of system calls are as follows:

• Process Control:  These types of system calls are used to control the processes. Some examples are end, abort, load, execute, create process, terminate process etc.

• File Management:  These types of system  calls are used to manage files. Some examples are Create file, delete file, open, close, read, write etc.

• Device  Management:  These  types  of system  calls  are used  to manage  devices. Some examples are Request device, release device, read, write, get device attributes etc.

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