Thursday, July 22, 2010

Batch systems


A batch system is one in which jobs are bundles together with the instructions necessary to allow them to be proposed without user intervention.
The simple operating system also called monitor is system software responsible for interpreting and carrying out the instructions in the batch jobs. When the monitor started a job, it is finished. Such batch system is called stacked job or simple batch system.
Often magnetic tapes and drums were used to store intermediate data and compiled programs.
1. Advantages of batch systems
Ø Move much of the work of the operator to the computer
Ø Increased performance since it was possible for job to start as soon as the previous job finished
2. Disadvantages
Ø Execution time can be large from user's point of view.
Ø Due to lack of protection scheme, one batch job can affect pending jobs
Ø A job could corrupt the operating system thus may affect pending jobs
One difficulty with simple batch simple batch systems is that the computer still needs to read the deck of cards before it can begin to execute the job. This means that the CPU is idle (or nearly so) during these relatively slow operations.
Capabilities and Limitations of Computer
Computer is a device, which is capable of doing almost all the works, which can be programmed by the user. But there are some functions, which are impossible for a computer to perform. Following are some of the capabilities and limitations of computer:
Capabilities
(a) Computers can do jobs with 100% accuracy and in a very fast speed in comparison to any other devices or human.
(b) It is possible to show and do the things, which are impossible for humans.
(c) Computer provides faster and cheaper communication with the use of various commutation technologies.
(d) it can perform almost all the works but for any purpose, user must provide proper program and necessary hardware.
Limitations
(a) Computer is a dull machine. It doesn't have intelligence on it. So, whatever it does, that is with the help of programs and devices developed by human. If such assistances are not provided, it will not be able to perform the simple of the simplest works, too. If any error occurs in its structure or circuitry, then the output (result) given by it is wrong which is very hard to tackle . It can't distinguish between the good and bad inputs and outputs in comparing to human. So, it is often called 'idiot servant'.

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