~ INPUT OUTPUT MANAGEMENT~

~ INPUT OUTPUT MANAGEMENT~

The delay between submission and job completion (call

turnaround time) may result from the amount of computing needed, or

from delays before the operating system start to process the job.

The introduction of disk technology has help in this regard. Rather

then the cards being read from the card reader directly into memory

and then the job being process, cards are read directly from the card

reader onto the disk. The location of card images is recorded in a table

kept by the operating system. When the job is executed, the operating

systems satisfy its requests for card reader input by reading from the

disk. Similarly, when the job request to output a line, that line is

copied into a system buffer and is written to the disk. When the job is

completed the output is actually printed. This form of processing is

called spooling.