rinnakkaisväylät

Rinnakkaisväylät, known in English as parallel ports, are a type of computer interface that transfers multiple bits of data simultaneously over multiple wires. This contrasts with serial ports, which transfer data one bit at a time. The parallel port was commonly used for connecting peripherals such as printers, scanners, and external drives to computers.

The most prevalent standard for parallel ports was the IEEE 1284 standard, which defined several modes of operation including unidirectional Enhanced Parallel Port (EPP) and bidirectional Extended Capabilities Port (ECP). EPP allowed for faster data transfer than the original Centronics standard and supported two-way communication. ECP further enhanced this by offering direct memory access (DMA) capabilities, allowing peripherals to transfer data directly to and from the computer's memory without involving the CPU as heavily.

Historically, the parallel port utilized a DB-25 connector on the computer side and a Centronics 36-pin connector on the printer side. While highly effective for its time, the parallel port has largely been superseded by serial interfaces like USB (Universal Serial Bus) due to USB's higher speeds, greater versatility, hot-plugging capabilities, and smaller connector size. Despite its decline in mainstream use, parallel ports can still be found on some industrial equipment and older legacy systems.