asynchronous input output

Asynchronous I/O, or non-blocking I/O, is a form of input/output processing that permits other processing to continue before the transmission has finished.Input and Output operations on a computer can be extremely slow compared to the processing of data. An I/O device can incorporate mechanical devices which must physically move, such as a hard drive seeking a track to read or write; extremely slow compared to merely moving electrons. For example, during a disk operation that takes ten milliseconds to perform, a processor that is clocked at one gigahertz could have performed ten million instruction-processing cycles.
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