I/O ports – What are input/output ports

A port is an interface between the computer and the peripheral devices. Also referred as I/O ports, and I/O port address, the input/output port allows the computer to communicate with hardware devices attached to the computer through these ports.

Ports are of two types

Internal port – These are present inside the CPU case on the motherboard and connect the motherboard to internal devices like hard disk drive, CD drive, internal modem, etc.

External port − These are present externally on the CPU case and connects the motherboard to external devices like modem, mouse, printer, flash drives, etc.

Commonly used Input/output ports are

Parallel ports

As the name depicts parallel ports send multiple bits of data at once. To do this, parallel ports require multiple data lines in their cables and port connectors. Parallel ports can send or receive 8 bits or 1 byte at a time. Parallel ports are used to connect printer, external hard disk drive, scanner, etc. They come in the form of 25-pin female pins.

parallel port

Serial ports

Serial ports just sends one bit at a time, so unlike parallel ports they only require single data line. Serial ports are usually 9-pin or 25-pin male connectors. They are also known as COM (communication) ports.

serial ports

USB Port

USB stands for Universal Serial Bus. It is the industry standard for short distance digital data connection. USB port is a standardized port to connect a variety of devices like printer, camera, keyboard, speaker, etc.


PS/2 port

PS/2 ports are 6 pin connectors used to connect keyboard and mouse to the computer. PS/2 was introduced by IBM to connect mouse and keyboard to personal computers. This port is now mostly obsolete and is replaced by USB port.

PS2 ports

However some advantages of PS/2 port are

  1. PS/2 ports may be favored for security reasons in a corporate environment as they allow USB ports to be totally disabled, preventing the connection of any USB removable disks and malicious USB devices.
  2. Some USB keyboards may not be able to operate the BIOS on certain motherboards due to driver issues or lack of support. The PS/2 interface has near-universal compatibility with BIOS.

Infrared Port

Infrared port port enables wireless exchange of data within a radius of 10m. Two devices that have infrared ports are placed facing each other so that beams of infrared lights can be used to share data.

Bluetooth Port

Bluetooth facilitates wireless connection between phones, computers and other digital devices over a short range. Bluetooth port enables synchronization between Bluetooth-enabled devices. There are two types of Bluetooth ports −

  1. Incoming− It is used to receive connection from Bluetooth devices.
  2. Outgoing− It is used to request connection to other Bluetooth device

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Click here to learn about BIOS.

Click here to learn about motherboard.


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