parallel port, what is parallel port, how parallel port works
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What is parallel port and how it works?

A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port. The IEEE 1284 standard defines the bi-directional version of the port. This transmits particular amount of bits in parallel at the same time. This is opposite to serial transition where one bit will be transmitted at a time.

Before the advent of USB, the parallel interface was adapted to access a number of peripheral devices other than printers. Probably one of the earliest devices to use parallel were dongles used as a hardware key form of software copy protection. Zip drives and scanners were early implementations followed by external modems, sound cards, webcams, gamepads, joysticks and external hard disk drives and CD-ROM drives. Adapters were available to run SCSI devices via parallel. Other devices such as EPROM programmers and hardware controllers could be connected parallel.

At the consumer level, the USB interface-and in some cases Ethernet-has effectively replaced the parallel printer port. Many manufacturers of personal computers and laptops consider parallel to be a legacy port and no longer include the parallel interface. USB to parallel adapters are available to use parallel-only printers with USB-only systems. However, due to the simplicity of its implementation, it is often used for interfacing with custom-made peripherals.

On PCs, the parallel port uses a 25-pin connector (type DB-25) and is used to connect printers, computers and other devices that need relatively high bandwidth. It is often called a Centronics interface after the company that designed the original standard for parallel communication between a computer and printer.

A newer type of parallel port, which supports the same connectors as the Centronics interface, is the EPP (Enhanced Parallel Port) or ECP, Extended Capabilities Port. Both of these parallel ports support bi-directional communication and transfer rates ten times as fast as the Centronics port.

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