Batch Operating System

Batch Operating System:

In the early days this system was used. Those days,  the jobs were placed in a job queue and the memory allocate managed the primary memory space, when space was available in the main memory, a job was selected from the job queue and it was loaded into memory. Once the job loaded into primary memory, it competes for the processor. When the processor became available, the processor scheduler selects job that was loaded in the memory and execute it. In batch processing is implemented to provide a batch file processing. So in this approach files of the similar batch are processed to speed up the task. It resulted in improved system utilization and performance of machine,  due to reduced turnaround time of execution job.


 

 

 

 

 


 

 

In batch processing system, earlier the jobs were scheduled in the order of their arrival that first comes first out(FIFO) / FCFS.  This scheduling method was easy and simple to implement but unbalanced for the situations where long jobs are queued ahead of the short jobs. To overcome this problem, another scheduling method named as Shortest Job First was used. As memory management is concerned, the main memory was partitioned into two fixed partitions. The lower end of this partition was assigned to the resident portion of the OS that is named as Batch Monitor. Whereas, the other partition/ higher end was assigned to the user programs. It was an improved technique in reducing the system setup time but still there were some limitations with this technique like as under-utilization of CPU time, non-interactivity of user with the running jobs etc. In batch processing system, the jobs of a batch were executed one after another. But while these jobs were performing input and output operations, many time the CPU was sitting idle resulting to low utilization  of resource.

The .bat extension used by Microsoft for batch files. This extension runs with DOS and all versions of Windows, under COMMAND.COM

Examples Disk operating System (DOS), IBM OS/2, Windows- 95, 98 etc.


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