What are serial and parallel ports and how do they work?

What are serial and parallel ports and how do they work?

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

What are 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 resembles the following (DB9 and DB25 connectors, respectively):

DB9 connector
DB25 connector

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

What are 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. 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 recognize 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
do you want to know more about computer hardware? check out our forum!