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1.1 BATCH SYSTEMS:
The users of batch operating system do not interact with the computer directly.
Each user prepares his job on an off-line device like punch cards and submits it to the computer operator. To speed up processing, jobs with similar needs are batched together and run as a group. Thus, the programmers left their programs with the operator. The operator then sorts programs into batches with similar requirements.
Each user prepares his job on an off-line device like punch cards and submits it to the computer operator. To speed up processing, jobs with similar needs are batched together and run as a group. Thus, the programmers left their programs with the operator. The operator then sorts programs into batches with similar requirements.
- The problems with Batch Systems are following.
- Lack of interaction between the user and job.
- CPU is often idle, because the speeds of the mechanical I/O devices is slower than CPU.
- Difficult to provide the desired priority
1.2 MULTIPROGRAMMED SYSTEMS
1.A multi-tasking or multiprogrammed operating system allows more than one program to be running at the same time, from the point of view of human time scales.
2.Multi-tasking can be of two types: pre-emptive and co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking. 32-bit versions of both Windows NT and Win9x, used pre-emptive multi-tasking. Mac OS prior to OS X used to support cooperative multitasking.As people wanted to multi task,this operating system emerged, so as to satisfy the demand.
2.Multi-tasking can be of two types: pre-emptive and co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking. 32-bit versions of both Windows NT and Win9x, used pre-emptive multi-tasking. Mac OS prior to OS X used to support cooperative multitasking.As people wanted to multi task,this operating system emerged, so as to satisfy the demand.
1.3 TIME-SHARING SYSTEMS
Time sharing is a technique which enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multiprogramming. Processor's time which is shared among multiple users simultaneously is termed as time-sharing. The main difference between Multiprogrammed Batch Systems and Time-Sharing Systems is
that in case of Multiprogrammed batch systems, objective is to maximize processor use, whereas in Time-Sharing Systems objective is to minimize response time.
Multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently.
Thus, the user can receives an immediate response.
For example, in a transaction processing, processor execute each user program in a short burst or quantum of computation.
That is if n users are present, each user can get time quantum. When the user submits the command, the response time is in few seconds at most.
Operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of a time.
Computer systems that were designed primarily as batch systems have been modified to time-sharing systems.
that in case of Multiprogrammed batch systems, objective is to maximize processor use, whereas in Time-Sharing Systems objective is to minimize response time.
Multiple jobs are executed by the CPU by switching between them, but the switches occur so frequently.
Thus, the user can receives an immediate response.
For example, in a transaction processing, processor execute each user program in a short burst or quantum of computation.
That is if n users are present, each user can get time quantum. When the user submits the command, the response time is in few seconds at most.
Operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of a time.
Computer systems that were designed primarily as batch systems have been modified to time-sharing systems.
Advantages of Timesharing operating systems are following
- Provide advantage of quick response.
- Avoids duplication of software.
- Reduces CPU idle time.
Disadvantages of Timesharing operating systems are following.
- Problem of reliability.
- Question of security and integrity of user programs and data.
- Problem of data communication.
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