Difference between revisions of "Batch operating system"
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The earliest batch OS's were not [[multi-tasking]]; each job ran to completion, before the next job started. However, this does not make efficient use of a system; while a job is waiting for [[input/output|I/O]] to complete, the rest of the system is idle. This was especially a problem for the very expensive computers which were the norm at that stage. | The earliest batch OS's were not [[multi-tasking]]; each job ran to completion, before the next job started. However, this does not make efficient use of a system; while a job is waiting for [[input/output|I/O]] to complete, the rest of the system is idle. This was especially a problem for the very expensive computers which were the norm at that stage. | ||
| − | So multi-tasking was added, because having a mix of jobs running at any time is the best way to maximize the use of the system. However, this brought in other issues: e.g. in the earliest stages of this change, all jobs which were running at any time had to be resident in [[main memory]] together. | + | So multi-tasking was added, because having a mix of jobs running at any time is the best way to maximize the use of the system. However, this brought in other issues: e.g. in the earliest stages of this change, all jobs which were running at any time had to be resident in [[main memory]] together. This then required the addition of security, so that a job which encountered a programing mistake could not damage other job(s). |
With the advent of [[time-sharing]] and [[virtual memory]], all modern OS's tend to have the capability to run jobs in batch mode, and so specialized batch OS's are now fading out. | With the advent of [[time-sharing]] and [[virtual memory]], all modern OS's tend to have the capability to run jobs in batch mode, and so specialized batch OS's are now fading out. | ||
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Revision as of 23:20, 29 September 2018
Batch operating systems were the first OS's, and were common up the 1980s or so; some are still running today.
The essence of a batch OS is its lack of interaction with users; a job - a program, along with all its input data - is handed in to the system; when there is an opportunity, it is run; and any resultant output is provided back to the person who sumitted the job.
The earliest batch OS's were not multi-tasking; each job ran to completion, before the next job started. However, this does not make efficient use of a system; while a job is waiting for I/O to complete, the rest of the system is idle. This was especially a problem for the very expensive computers which were the norm at that stage.
So multi-tasking was added, because having a mix of jobs running at any time is the best way to maximize the use of the system. However, this brought in other issues: e.g. in the earliest stages of this change, all jobs which were running at any time had to be resident in main memory together. This then required the addition of security, so that a job which encountered a programing mistake could not damage other job(s).
With the advent of time-sharing and virtual memory, all modern OS's tend to have the capability to run jobs in batch mode, and so specialized batch OS's are now fading out.
