What is Operating System, its types and different services?

What is Operating System, its types and different services?

Operating system is software that is required in order to run application programs and utilities. It works as a bridge to perform better interaction between application programs and hardware of the computer. Examples of operating system are UNIX, MS-DOS, MS-Windows – 98/XP/Vista, Windows-NT/2000, OS/2 and Mac OS.

Following are some of important functions of an operating System:

Memory Management

Processor Management

Device Management

File Management


Control over system performance

Job accounting

Error detecting aids

Coordination between other software and users

Different types of operating system:

There are different types of operating system those are organized by their Working:

1.Serial Processing: In Serial Processing operating system that use FIFO (First in First Out) technique for processing the process.
Example: Windows 95 and Windows 98

2.Batch Processing: In batch processing a similar type of jobs prepared and processed.

Example:IBM’s OS360, Payroll System, Bank Statements etc

3.Multi-Programming: In Multi programming Operating System Multiple Programs are Executed on the System at a Time.

Example: Windows 10 etc,

4.Real Time System: Real Time System are used there Requires fast and Timely Response.

Example:Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc

5.Distributed Operating System: In this Operating system Data is Stored and Processed on Multiple Locations.

Example: LOCUS etc

6.Multiprocessing: In This type of operating system there are two or More CPU in a Single OS.

Example:Windows NT, 2000, XP, and Unix

7.Parallel operating systems: It manages all running resources of the computer system in parallel

Example:UNIX and Windows NT etc.

Services provided by operating system:

An Operating System provides services to both the users and to the programs.

It provides programs an environment to execute.

It provides users the services to execute the programs in a convenient manner.

Following are a few common services provided by an operating system −

Program execution

I/O operations

File System manipulation


Error Detection

Resource Allocation


Each service is described below with example:

Program execution

Operating systems handle many kinds of activities from user programs to system programs like printer spooler, name servers, file server, etc. Each of these activities is encapsulated as a process.

A process includes the complete execution context (code to execute, data to manipulate, registers, OS resources in use). Following are the major activities of an operating system with respect to program management −

Loads a program into memory.

Executes the program.

Handles program’s execution.

Provides a mechanism for process synchronization.

Provides a mechanism for process communication.

Provides a mechanism for deadlock handling.

I/O Operation

An I/O subsystem comprises of I/O devices and their corresponding driver software. Drivers hide internal complexities of specific hardware devices from the users.

An Operating System manages the communication between user and device drivers.

I/O operation means read or write operation with any file or any specific I/O device.

Operating system provides the access to the required I/O device when required.

File system manipulation

A file represents a collection of related information. Computers can store files on the disk (secondary storage), for long-term storage purpose. Examples of storage media include magnetic tape, magnetic disk and optical disk drives like CD, DVD. Each of these media has its own properties like speed, capacity, data transfer rate and data access methods. Operating System provides an interface to create the backup of file system.


In case of distributed systems which are a collection of processors that do not share memory, peripheral devices, or a clock, the operating system manages communications between all the processes. Multiple processes communicate with one another through communication lines in the network.

Communication may be implemented by two methods, either by Shared Memory or by Message Passing.

Error handling

Errors can occur anytime and anywhere. An error may occur in CPU, in I/O devices or in the memory hardware. Following are the major activities of an operating system with respect to error handling −

The OS constantly checks for possible errors.

The OS takes an appropriate action to ensure correct and consistent computing.

Resource Management

In case of multi-user or multi-tasking environment, resources such as main memory, CPU cycles and files storage are to be allocated to each user or job. Following are the major activities of an operating system with respect to resource management −

The OS manages all kinds of resources using schedulers.

CPU scheduling algorithms are used for better utilization of CPU.


Considering a computer system having multiple users and concurrent execution of multiple processes, the various processes must be protected from each other’s activities.

Protection refers to a mechanism or a way to control the access of programs, processes, or users to the resources defined by a computer system. Following are the major activities of an operating system with respect to protection −

The OS ensures that all access to system resources is controlled.

The OS ensures that external I/O devices are protected from invalid access attempts.

The OS provides authentication features for each user by means of passwords.


Next: Operating system properties