Concept of Operating System | BCA 1st Year 2024 | 2nd Semester

Operating System

    Operating system is an interface between user and computer hardware.

Goals of Operating system

1.Primary  2.Secondary

1.Primary:-  The primary objective of an operating system is to make computer systems convenient to use.

2.Secondary:-  The Secondary objective of an operating system is to utilize computer hardware in a efficient manner. 

👉 some popular operating systems are window, linux, macos.

Functions of operating system-

• Process Management
• File Management
• Security
• Memory Management
• Device Management

Process Management:- A program is written in any language in execution state is called Process.

    in multiprogramming environment the operating system decides which process gets the processer when and for how much time.

File Management:- it manages all the files related activities such as storage retrieval, naming, sharing and protection of files.

Memory Management:-  it is the management of the main or primary memory whatever program is executed.

    it has to be present in the main memory,therefor there can be more than one program present at a time 

Hence,it is required to manage the memory.  

Security:- Operatimg system makes sure that only authorized users get access to the computer and it's data.

Device Management:-An operating system manages device communication their respective drivers. Device management keeps tarck of all device.

Types of operating systems -

There are five types of operating systems --

• Batch operating system
• Real Time operating system
• Multiprogramming operating system
• Multitasking operating system
• Distributed operating system

Batch operating system:-  This type of operating system does not interact with computer directly, there is an operator which takes similar jobs having the same requirement & group them into batches.

Advantage :-

• Multi-user can share the batch system.
• The idle time for the batch system is very less.

Disadvantage :-

• It is some time costly.
• The other jobs will have to wait for an unknown time if any job fails.

Real Time Operating system :- This type of operating system serve real time system, The time interval required to process and respond to input is very small. the time interval is called respond time.

    Real time operating system are used when there are time requirements that are very strict like missile system, traffic control system, robot etc.

Types of real time operating system -----

there are two types of real time operating system :

Hard Real Time :-   These operating system are meant for application where time constraints are very strict and even the shortest possible delay is not acceptable.

Soft Real Time :-  These operating systems are for application where for time constraints is very less strict.

Advantage :-

• These type of operating systems are error free.
• Maximum utilization of device and system more output from all the resources.

Multi-programming Operating system :-  A multi-programming operating system may run many program on a single processer computer.

    it execute multiple program to avoid CPU and memory under utilization. it is also called multi-program task system.

Advantage :-

• CPU never become idle.
• Efficient resource utilization .
• Short-time job completed faster than long time jobs.

Disadvantage :-

• Long time Job have to wait long.
• CPU scheduling is required.
• User interaction not possible during program execution.

Multi-tasking operating system :- These system are also known as time-sharing operating system.

    Each task is given some time to execute so that all the task works smoothly. the time that each task gets to execute is called quantum.

Advantage :-

• Each task gets an equal opportunity.
• CPU idle time can be reduced.

Disadvantage :-

• Reliability problem.
• Data communication problem. 

Distributed operating system :- Distributed operating system uses many processer located in different machines to provide very fast computation to it's user.

    The processer communicate with one another through various communication line, processer in distributed system may vary in size and function.

Advantage :- 

• Delay in data processing reduced.
• load on host computer reduced.

Disadvantage :-

• if fails main network will stop the intire communication.
• they are very expensive.

Process -

Process :-  Process is the execution of a program that perform the action specified in that program.

    A process is an active entity as opposed to the programs which is considered to be a passive entity, process is execution of a program.

Process state -

New states :-  The process is being creative.

Ready states :- The process is waiting to be assign to a processer.

Running states :-  Instruction are being executed.

Waiting states :-  The process is waiting for some event to occur input/output completion or reception of a signal.

Terminated states :-  The process has finished execution.

Process Control Blocks :-  Each process is represented in the operating system by a process control block also called a task control block.

    Each block of memory contains information about the process state, program counter, stack pointer etc.

    A process control block contains information about the process, it contains many pieces of information associated with a specific process including these.......  

Process Control Blocks-

1.Pointer :-