Explain the concept of Spooling and Buffering?

Concept of Spooling

- In the field of computer science, the ‘simultaneous peripheral operations on – line’ has been shortened down to the acronym ‘spool’. 

- A SPOOL software such as that of the IBM’s ‘SPOOL system’ was used by the computer systems in the time period from late 1950 to early 1960. 

- From one medium to another, files could be copied using this software. For example:

1. From tape to punch card
2. From punch card to tape
3. From tape to printer
4. From one card to another card

- IBM released less expensive software called the IBM 1401 that from some time brought down the application of the spool software.

- The print spooling is the most common application of this concept.

- The documents to be printed are formatted and stored at an area of the disk and retrieved when the print command is given.

- The printer prints out these documents at its defined rate. 

- Typically, at a time only one document can be printed by a printer and for doing so it takes a few minutes or seconds depending up on how fast it is. 

- Spooling speeds up this process, but how? 

- With a spool software many documents can be written to the print queue by the multiple processes without having to wait. 

- As soon as the process wrote its document in the spooling device, it was free to carry out the other tasks. 

- At the same time another process would handle the printing of the document. 

- If there was no spooling, the processor would not be able to continue until and unless the pending process is finished. 

- This would lead to long waits during processing and thus making the paradigm inefficient.

Concept of Buffering

- The physical memory storage has a region where it temporarily stores the data when it is being sent to another location.

- Typically whenever data is taken from some input device such as a keyboard or a mouse, it is stored in the buffer before sending it to the processor or output device. 

- Buffers can be implemented either through some virtual data buffer or in a fixed memory location.

- In majority of the cases, implementation of buffers is done with software that point to some location in the physical memory and use faster RAM. 

- The data access from buffers is quite fast when compared to that of the hard disk drives. 

- Buffers are used wherever a difference occurs between the rate of receiving data and rate of processing it.

- It also occurs if the two data rates are variable such as in online video streaming, printer spooler and so on. 

- The timing in a buffer is adjusted with the implementation of a FIFO algorithm or we can say a queue in the memory. 

- This would allow at the same time to write the data at the one end and read it from another end and both being done at different rates.

- Buffers are used along with I/O to hardware like in transmitting and receiving data in a network, disk drives, playing some song on the speakers etc.

- Buffers used in telecommunication are called the telecommunication buffers and make use of a storage medium or buffer routine.

- This routine compensates for the two different rates while receiving and sending data. 

- Buffers are also used in making interconnections between digital circuits working at different rates, for making timing corrections, delaying transmission time and so on.