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Serial Port and Parallel port

Latest update on Friday 22 January 2021 à 11:45 by Elena Keracheva.

Every computer is built with tons of different ports that perform various functions. Two of the most important types for data trans are serial ports and parallel ports. This article discusses the differences and similarities between the two types of port.



Serial Ports

What is a serial port? Serial ports are generally built into the motherboard. This is why the connectors behind the casing that are connected to the motherboard by a wire cable can be used to connect an exterior element. A serial port connector generally has 9 or 25 pins and resemble the following (DB9 and DB25 connectors respectively):

DB9 connector
DB25 connector

A personal computer generally has between one and four serial ports.

Parallel Ports

Parallel data transmission involves sending data simultaneously on several channels (wires). The parallel ports on personal computers can be used to send 8 bits (one octet) simultaneously via 8 wires:

transmission on a parallel port

The first two-way parallel ports allowed for speeds of 2.4Mb/s. Enhanced parallel ports have been developed however to achieve higher speeds — the EPP (Enhanced Parallel Port) achieves speeds of 8 to 16 Mbps, and the ECP (Enhanced Capabilities Port), developed by Hewlett Packard and Microsoft has the same characteristics as the EPP, with a Plug and Play feature, allowing the computer to recognise the connected peripherals.

Parallel ports, like serial ports, are built into the motherboard. DB25 connectors allow for connection to an exterior element (e.g. a printer):

DB25 connector


Image: © Signs and Symbols - Shutterstock.com/www.virtual-serial-port.org
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