The port is usually on the back of the computer and is part of the motherboard. Due to the parallel transmission of the data, they can be forwarded much faster (4, 8 and 16 bits can be transmitted at the same time) than with serial interfaces. If the clock rate increases and the number of bits increases, the synchronization between bits with different cable lengths can be impaired. Since the parallel port is significantly slower than a USB connection, it is rarely used on newer computers these days. Which parallel ports are there? There is the Centronics interface, Advanced Technology Attachment (ATA), IEEE 1284 with the Extended Capability Port (ECP) and the Standard Parallel Port (SPP) and many more. The interfaces are used as protocols for CD drives, scanners, printers and other peripheral devices. The Apple Macintosh computer uses SCSI as an interface, which is parallel, but a lot more flexible than the parallel port.