WHAT IS SPOOLING AND BUFFERING


Spooling:- 

                              A spool is a buffer that holds output for a device, such as a printer, that cannot accept interleaved data streams. Spooling is the process in which jobs from the to the disk and the location of that card in the disk is recorded in a table by the operating system. When that job is required for execution, it is read from the disk .


Similarly, when job required a printer for output a line, that particular line is copied onto the disk and system buffer, and at the completion of job output is read from disk and printed by the printer.

Some devices, such as tape drive and printer, cannot useful multiplex the I/O request of multiple concurrent applications. Spooling is one way that OS can coordinate concurrent output. Another way to deal with concurrent dives access is for provide ding explicit facilities for coordinating some OS provided support it is called spooling.

Buffering:- 

                               A buffer is a memory area that stores data while they are transferred between two devices or between a device and an application Buffering is done for these reason. First reason is to cope with a speed mismatch between consumer and producer of a data stream. Suppose , for example, that a file is being received via modem  for memory on the hard disk. When an entire buffer of data has arrived, the buffer can received from modem.
The second use of buffering is to adapt between devices that have different data-transfer sizes. Such disparities are especially common in computer networking, whenever  buffers are used widely for fragmented and packets,at sending side. These packets are sent over the network, and the receiving   side places them in a reassembly buffer to from an image of the source data.

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