Mainframe system were use to solve commercial problems. It may be simple batch system, multi programmed system, time sharing, or time sharing system. We discuss all of these with detail. It is also used to solve our scientific problems.
Here following is complete description of this system:
Types of mainframe computer operating system
- Simple Batch System
- Multi Programmed system
- Time Sharing
- Time Sharing system
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| operating system |
Simple Batch System
Every computer were run according to given instruction. Tape drives and card reader were two input devices. Card, Line printer and tape drives punched were common some output devices. The user did not interact with computer directly.
First of all, the user ready a job that consist of data, program and some control information. He then submitted it to computer in the form of punched cards.
An operating system was a simple system. Its basic transfer control from one job to other jobs automatically. The operating was always coded in memory. The operator batched this jobs and run into computer to speed up.
In this environment, central processing unit is idle as speed of input and output devices is much slower than central processing unit. After a few time, the introduction of disk resulted is much faster input output devices. In disk task operating enter all jobs in disk instead of card reader. With the help of job scheduling all jobs performed efficiently result.Job scheduling is possible because in this process all jobs are in disk.
VMS is an example of batch operating system.
Multi-Programmed System
Job pool is a group of jobs that are ready for execution. Suppose that there is more than one jobs in sequence the operating system to make the decision about which jobs to execute next.
In this situation, it is not possible for single user to keep central processing unit or input and output busy at same time. Multi-programmed allow the central processing unit execute all jobs according to there need.
The CPU is group of jobs. Now currently execute job on waiting if a job is already in executing phase. after it another job select and central processing unit now it execute. This process continue even all jobs execute.
And the other hand, in Non-Multi-programming system, if a job on wait for input and output operation, CPU would also have to wait until input output was end.
Some jobs will fit on memory but some jobs may have to remain a disk. The operating system be able to perform jobs in pool. Sometimes, many jobs run at same time the operating system must be control them.Central processing unit must be able to decide which job execute first and which job execute next.
Time Sharing
In simple batch system, a person can not interconnection with jobs when these are execute. It means that all possible problems can not solve easily when these jobs are execute. Another problem debugging of a program. we know that all debugging static.
Using the time sharing batch computer become more interactive. Central Processing unit is the most important that is shared. Each job can pick central processing unit after its execution other one ready for execution.
Time sharing allow the interact with jobs when it is executing.The communication can occur with keyboard using a commands. The user must know the status of the job in order to enter relevant command.The output of jobs always show on screen.
Time Sharing System
Time sharing is a multi-process, multi-user and interactive system. It allow the multi user to used the operating system in same time. The computer first work for first user who task first time. It than goes to the other user task. Each jobs gets a time slice in round robin. This process is continue until the slice not end. The task stop when given slice time end.
A time sharing system is very difficult. It is most difficult than multi programmed. Using a virtual memory it worked. The technique that allow the multiple jobs compliantly is called virtual memory.
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