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Module I
Operating Systems –
An Operating System (OS) is an interface between a computer user and computer hardware.
An operating system is a software which performs all the basic tasks like file management,
memory management, process management, handling input and output, and controlling
peripheral devices such as disk drives and printers.
Some popular Operating Systems include Linux Operating System, Windows Operating
System, VMS, OS/400, AIX, z/OS, etc.
Definition-
An operating system is a program that acts as an interface between the user and the computer
hardware and controls the execution of all kinds of programs.
Types-
There are several types of Operating Systems which are mentioned below.
1. Batch Operating System
This type of operating system does not interact with the computer directly. There is an
operator which takes similar jobs having the same requirement and groups them into
batches. It is the responsibility of the operator to sort jobs with similar needs.
Advantages of Batch Operating System
, It is very difficult to guess or know the time required for any job to complete.
Processors of the batch systems know how long the job would be when it is in the
queue.
Multiple users can share the batch systems.
The idle time for the batch system is very less.
It is easy to manage large work repeatedly in batch systems.
Disadvantages of Batch Operating System
The computer operators should be well known with batch systems.
Batch systems are hard to debug.
It is sometimes costly.
The other jobs will have to wait for an unknown time if any job fails.
Examples of Batch Operating Systems: Payroll Systems, Bank Statements, etc.
2. Multi-Programming Operating System
Multiprogramming Operating Systems can be simply illustrated as more than one program
is present in the main memory and any one of them can be kept in execution. This is
basically used for better execution of resources.
Advantages of Multi-Programming Operating System
Multi Programming increases the Throughput of the System.
It helps in reducing the response time.
Disadvantages of Multi-Programming Operating System
There is not any facility for user interaction of system resources with the system.
3. Multi-Processing Operating System
Multi-Processing Operating System is a type of Operating System in which more than one
CPU is used for the execution of resources. It betters the throughput of the System.
Advantages of Multi-Processing Operating System
It increases the throughput of the system.
As it has several processors, so, if one processor fails, we can proceed with another
processor.
Disadvantages of Multi-Processing Operating System
Due to the multiple CPU, it can be more complex and somehow difficult to understand.
,4. Multi-Tasking Operating System
Multitasking Operating System is simply a multiprogramming Operating System with
having facility of a Round-Robin Scheduling Algorithm. It can run multiple programs
simultaneously.
There are two types of Multi-Tasking Systems which are listed below.
Preemptive multi-tasking
Cooperative multi-tasking
Advantages of Multi-Tasking Operating System
Multiple Programs can be executed simultaneously in Multi-Tasking Operating System.
It comes with proper memory management.
Disadvantages of Multi-Tasking Operating System
The system gets heated in case of heavy programs multiple times.
5. Time-Sharing Operating Systems
Each task is given some time to execute so that all the tasks work smoothly. Each user gets
the time of the CPU as they use a single system. These systems are also known as
Multitasking Systems. The task can be from a single user or different users also. The time
that each task gets to execute is called quantum. After this time interval is over OS switches
over to the next task.
Time-Sharing OS
Advantages of Time-Sharing OS
Each task gets an equal opportunity.
Fewer chances of duplication of software.
CPU idle time can be reduced.
, Resource Sharing: Time-sharing systems allow multiple users to share hardware
resources such as the CPU, memory, and peripherals, reducing the cost of hardware and
increasing efficiency.
Improved Productivity: Time-sharing allows users to work concurrently, thereby
reducing the waiting time for their turn to use the computer. This increased productivity
translates to more work getting done in less time.
Improved User Experience: Time-sharing provides an interactive environment that
allows users to communicate with the computer in real time, providing a better user
experience than batch processing.
Disadvantages of Time-Sharing OS
Reliability problem.
One must have to take care of the security and integrity of user programs and data.
Data communication problem.
High Overhead: Time-sharing systems have a higher overhead than other operating
systems due to the need for scheduling, context switching, and other overheads that
come with supporting multiple users.
Complexity: Time-sharing systems are complex and require advanced software to
manage multiple users simultaneously. This complexity increases the chance of bugs
and errors.
Security Risks: With multiple users sharing resources, the risk of security breaches
increases. Time-sharing systems require careful management of user access,
authentication, and authorization to ensure the security of data and software.
Examples of Time-Sharing OS with explanation
IBM VM/CMS: IBM VM/CMS is a time-sharing operating system that was first
introduced in 1972. It is still in use today, providing a virtual machine environment that
allows multiple users to run their own instances of operating systems and applications.
TSO (Time Sharing Option): TSO is a time-sharing operating system that was first
introduced in the 1960s by IBM for the IBM System/360 mainframe computer. It
allowed multiple users to access the same computer simultaneously, running their own
applications.
Windows Terminal Services: Windows Terminal Services is a time-sharing operating
system that allows multiple users to access a Windows server remotely. Users can run
their own applications and access shared resources, such as printers and network
storage, in real-time.
Module I
Operating Systems –
An Operating System (OS) is an interface between a computer user and computer hardware.
An operating system is a software which performs all the basic tasks like file management,
memory management, process management, handling input and output, and controlling
peripheral devices such as disk drives and printers.
Some popular Operating Systems include Linux Operating System, Windows Operating
System, VMS, OS/400, AIX, z/OS, etc.
Definition-
An operating system is a program that acts as an interface between the user and the computer
hardware and controls the execution of all kinds of programs.
Types-
There are several types of Operating Systems which are mentioned below.
1. Batch Operating System
This type of operating system does not interact with the computer directly. There is an
operator which takes similar jobs having the same requirement and groups them into
batches. It is the responsibility of the operator to sort jobs with similar needs.
Advantages of Batch Operating System
, It is very difficult to guess or know the time required for any job to complete.
Processors of the batch systems know how long the job would be when it is in the
queue.
Multiple users can share the batch systems.
The idle time for the batch system is very less.
It is easy to manage large work repeatedly in batch systems.
Disadvantages of Batch Operating System
The computer operators should be well known with batch systems.
Batch systems are hard to debug.
It is sometimes costly.
The other jobs will have to wait for an unknown time if any job fails.
Examples of Batch Operating Systems: Payroll Systems, Bank Statements, etc.
2. Multi-Programming Operating System
Multiprogramming Operating Systems can be simply illustrated as more than one program
is present in the main memory and any one of them can be kept in execution. This is
basically used for better execution of resources.
Advantages of Multi-Programming Operating System
Multi Programming increases the Throughput of the System.
It helps in reducing the response time.
Disadvantages of Multi-Programming Operating System
There is not any facility for user interaction of system resources with the system.
3. Multi-Processing Operating System
Multi-Processing Operating System is a type of Operating System in which more than one
CPU is used for the execution of resources. It betters the throughput of the System.
Advantages of Multi-Processing Operating System
It increases the throughput of the system.
As it has several processors, so, if one processor fails, we can proceed with another
processor.
Disadvantages of Multi-Processing Operating System
Due to the multiple CPU, it can be more complex and somehow difficult to understand.
,4. Multi-Tasking Operating System
Multitasking Operating System is simply a multiprogramming Operating System with
having facility of a Round-Robin Scheduling Algorithm. It can run multiple programs
simultaneously.
There are two types of Multi-Tasking Systems which are listed below.
Preemptive multi-tasking
Cooperative multi-tasking
Advantages of Multi-Tasking Operating System
Multiple Programs can be executed simultaneously in Multi-Tasking Operating System.
It comes with proper memory management.
Disadvantages of Multi-Tasking Operating System
The system gets heated in case of heavy programs multiple times.
5. Time-Sharing Operating Systems
Each task is given some time to execute so that all the tasks work smoothly. Each user gets
the time of the CPU as they use a single system. These systems are also known as
Multitasking Systems. The task can be from a single user or different users also. The time
that each task gets to execute is called quantum. After this time interval is over OS switches
over to the next task.
Time-Sharing OS
Advantages of Time-Sharing OS
Each task gets an equal opportunity.
Fewer chances of duplication of software.
CPU idle time can be reduced.
, Resource Sharing: Time-sharing systems allow multiple users to share hardware
resources such as the CPU, memory, and peripherals, reducing the cost of hardware and
increasing efficiency.
Improved Productivity: Time-sharing allows users to work concurrently, thereby
reducing the waiting time for their turn to use the computer. This increased productivity
translates to more work getting done in less time.
Improved User Experience: Time-sharing provides an interactive environment that
allows users to communicate with the computer in real time, providing a better user
experience than batch processing.
Disadvantages of Time-Sharing OS
Reliability problem.
One must have to take care of the security and integrity of user programs and data.
Data communication problem.
High Overhead: Time-sharing systems have a higher overhead than other operating
systems due to the need for scheduling, context switching, and other overheads that
come with supporting multiple users.
Complexity: Time-sharing systems are complex and require advanced software to
manage multiple users simultaneously. This complexity increases the chance of bugs
and errors.
Security Risks: With multiple users sharing resources, the risk of security breaches
increases. Time-sharing systems require careful management of user access,
authentication, and authorization to ensure the security of data and software.
Examples of Time-Sharing OS with explanation
IBM VM/CMS: IBM VM/CMS is a time-sharing operating system that was first
introduced in 1972. It is still in use today, providing a virtual machine environment that
allows multiple users to run their own instances of operating systems and applications.
TSO (Time Sharing Option): TSO is a time-sharing operating system that was first
introduced in the 1960s by IBM for the IBM System/360 mainframe computer. It
allowed multiple users to access the same computer simultaneously, running their own
applications.
Windows Terminal Services: Windows Terminal Services is a time-sharing operating
system that allows multiple users to access a Windows server remotely. Users can run
their own applications and access shared resources, such as printers and network
storage, in real-time.
