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programmed input output (PIO)

Programmed Input Output(PIO) is an older transfer protocol for communication between the central processing unit( CPU) and peripheral devices such as hard disk drives, removable disk drives and floppy disk drives. PIO places an enormous load on the computer's central processing unit, since it controls the exchange of information between RAM and mass storage, which is reflected in the data transfer rate.

The PIO mode determines the transfer rates of the Integrated Drive Electronics( IDE). There are several PIO modes with transfer rates between 3.33 MB/s and 16.6 MB/s: PIO mode 0 provides transfer rates up to 3.33 MB/s at a cycle time of 600 ns, mode 1 up to 5.22 MB/s at a cycle time of 383 ns, mode 2 up to 8.33 MB/s at a cycle time of 240 ns, mode 3 achieves 11.11 MB/s at a cycle time of 180 ns and mode 4 16.6 MB/s at 120 ns cycle time.

PIO modes and their transfer rates

PIO modes and their transfer rates

PIO Mode 4 is supported by newer CD drives. The successor protocol to PIO is Direct Memory Access( DMA) as Ultra-DMA( UDMA). Another PIO mode variant is the planned Mode 5 with 20 MB/s.

Informations:
Englisch: programmed input output - PIO
Updated at: 27.03.2008
#Words: 183
Links: parallel input/output (electronic unit) (PIO), protocol, communication (COM), central processing unit (CPU), central processing unit (CPU)
Translations: DE
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