What is a multitasking operating system

The operating system that runs more than one task at a time is known as a multitasking operating system (MOS). MOS can be desktop or mobile operating system (OS).

Different tasks run in the OS are MS Word, MS Excel, email application, browser, media player, OS services etc. End users use all these programs at the same time. But OS takes this concept little different. Let me explain this concept by a diagram.

Diagram of multitasking in operating system

As shown in the diagram above, three tasks are running on the computer. CPU gives 10 nanoseconds to each task. Time is shared between task 1, task 2 and task 3. If task 1 is not completed in 10 nanoseconds then task 1 have to wait until task 2 and task 3 are given time.

Note that one processor (CPU) can only run one process (task) at a time. CPU gives small time to each process and switch to another process.

Now let me discuss some of the advantages and disadvantages of MOS.

Advantages of the multitasking operating system (MOS)


Time-sharing is the main concept and benefit of MOS. All tasks are given a suitable amount of time and no waiting time occurs for the CPU.

Handle multiple users:

Multiple users running multiple programs can be best handled by MOS. All programs run smoothly without a glitch in performance. All users of OS are given a suitable amount of time.

Protected memory:

Memory is better managed in MOS. Unauthorized applications are not given permission to overuse memory.

Efficient virtual memory:

If any program has long waiting time due to any I/O interrupt, that program is shifted to virtual memory. After completion of the I/O operation, the program comes back to RAM. The process of virtual memory management is nicely handled in MOS.

Programs can run in the background:

OS services and another type of background services are also given some time to run in the OS. These programs are not visible to a normal computer user. But these programs keep running to maintain other programs run smoothly. Example of background programs is a firewall, anti-virus protection programs etc.

Increase reliability:

OS runs smoothly in using multitasking. All type of computer users become satisfied. Either user can run a single program or multiple programs they don’t feel any fault in using a computer.

The user can use multiple programs:

Multiple programs like MS Word, MS Excel, Photoshop, browser, games, and calculator can run at the same time. This is a big advantage to MOS.

Best use of computer resources:

Computer resources like RAM, Processor, I/O devices, hard drive, and Gaming consoles are better managed in MOS.

Disadvantages of the multitasking operating system (MOS­)

There are some drawbacks of MOS also. Some of them are discussed below:

Limitation of memory:

When a computer user opens many programs at a time, the computer becomes slow. The reason behind is that many programs are loaded into main memory and CPU cannot give good time for each program and response time of completing the job becomes higher. Computers with low RAM usually face this problem. One solution to this is to increase your RAM capacity.

Limitation of the processor:

If the processor is slow in the computer then it can process programs slow and manage multiple programs takes longer time. Some heavy programs cannot run smoothly on the slow processor because they need more processing powers.

CPU heat up:

By doing multitasking, the processor becomes busy all the time and CPU heats up. To solve this problem you have to attach the cooling system to your CPU. This normally happens when you play heavy games on your PC.

Examples of multitasking operating system

  • Unix
  • Windows XP, Vista, 7, 8, 10

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