Difference between multitasking, multithreading and multiprocessing?

Question

Whats the difference between multitasking, multiprogramming & multiprocessing

This comes regularly for my university OS exams and I can\'t find a good answer. I

Answer 1

In a multiprogramming system, there are more than one programs loaded in main memory which are ready to execute. Only one program at a time is able to get the CPU for executing its instructions while all others are waiting their turn. The main idea of multiprogramming is to maximize the use of CPU time. Suppose currently running process is performing an I/O task, then OS may interrupt that process and give the control to one of the other in - main memory programs that are ready to execute (i.e. process context switching). In this way, no CPU time is wasted by system waiting for the I/O task to be completed.

MultiProcessing - Multiprocessing is the ability of an operating system to execute more than one process simultaneously on a multi processor machine. In multiprocessing system, a computer uses more than one CPU at a tme.

Multitasking - Multitasking is the ability of an operating system to execute more than one task simultaneously on single processor machine, these multiple tasks share common resources such as CPU and memory. In multitasking system, CPU switches from one task to next task so quickly that appears as all tasks are executing at the same time.

There are differences between multitasking and multi programming. A task in a multitasking system is not whole application program but it can refers to a "thread of execution" when one process is divided into sub-tasks. Each smaller task does not hijack the CPU until it finishes, they share a small amount of the CPU time called Quantum. Multi programming and multitasking operating systems are time sharing systems.

Multi threading - Multi threading is the extension of multitasking. Multi threading is the ability of an operating system to subdivide the specific operation within a single application into individual threads. Each of these threads can run in parallel. The OS divides processing time not only among different applications but also among each thread within an application.