With the parallel interface, the bits of a character or byte are transmitted simultaneously or in parallel. Each bit of a character is transmitted simultaneously via a separate line, via separate channels or on a channel in multiplex. Standardized interfaces such as V.20 and others exist for parallel data transmission in the telephone network.
Since parallel interfaces transmit data simultaneously on several parallel lines, they are superior to serial interfaces in data transmission rates. Since the latter transmit their data sequentially, one bit at a time.
The data transfer rate of parallel ports depends on the number of bits transferred in parallel. This can be 4, 8 or even 16, whereby with a higher number of bits and an increasing clock rate, the synchronization between the bits on the different lines is affected by the line length.
InPC technology, there are various parallel interfaces such as the Centronics interface, Advanced Technology Attachment( ATA), AT Attachment Packet Interface( ATAPI), IEEE 1284 with the Extended Capability Port ( ECP), the Standard Parallel Port( SPP), Enhanced Parallel Port ( EPP), the Line Printer Terminal( LPT) and Small ComputerSystem Interface ( SCSI). These interfaces are ports for printers, CD drives, scanners, and other peripherals.