Sunday, February 20, 2011

OS- Spooling and Buffering


Acronym for simultaneous peripheral operations on-line, spooling refers to putting jobs in a buffer, a special area in memory or on a disk where a device can access them when it is ready. Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.

pls do refer :

Spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.

Spooling refers to copying files in parallel with other work. The most common use is in reading files used by a job into or writing them from a buffer on a magnetic tape or a disk. Spooling is useful because devices access data at different rates.

The most common spooling application is print spooling .


buffer- A temporary storage area, usually in RAM. The purpose of most buffers is to act as a holding area, enabling the CPU to manipulate data before transferring it to a device.

Buffers are commonly used when burning data onto a compact disc, where the data is transferred to the buffer before being written to the disc.
Another common use of buffers is for printing documents. When you enter a PRINT command, the operating system copies your document to a print buffer (a free area in memory or on a disk) from which the printer can draw characters at its own pace. This frees the computer to perform other tasks while the printer is running in the background. Print buffering is called spooling.

A Buffer is a region of memory used to temporarily hold data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a keyboard) or just before it is sent to an output device (such as a printer). However, a buffer may be used when moving data between processes within a computer. This is comparable to buffers in telecommunication. Buffers can be implemented in either hardware or software, but the vast majority of buffers are implemented in software. Buffers are typically used when there is a difference between the rate at which data is received and the rate at which it can be processed, or in the case that these rates are variable, for example in a printer spooler.

Buffering: is reading and writing data from hdd takes long to improve the speed for data processing the data next required by processor is stored is cache memory or cpu register.for e.g. to cut certain line from text file to copy into another file.cut data get stored in to buffer (cpu register) to get back stored into another file.

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