Input/Output Device Interfaces | CompTIA IT Fundamentals FC0-U61 | 2.1

In this video you will be learning how to classify common types of input/output device interfaces such as networking, peripheral devices, and graphic devices.


Networking is the practice of interfacing two or more computing devices with each other for the purpose of sharing data.  In this section you will learn about two categories of network interfaces: wired & wireless.


A wired network interface requires a connection on the device and a connection to the local area network (LAN) or to the internet.  There are two types of connectors for a wired network interface:  

  • Registered Jack Function 11 (RJ-11) telephone connector
  • Registered Jack Function 45 (RJ-45) ethernet connector

The RJ-11 can connect to PCs, printers, & multifunctional devices directly to remote computers or to the internet via the telephone network.  The RJ-45 is more versatile. It can connect computers and devices to each other on a LAN or to the internet. RJ-11 cables generally have four to six wires, whereas RJ-45 cables have 8 wires.

Registered Jack 11 (RJ-11) Telephone Connector

The RJ-11 connector is more commonly known as a modem port, phone connector, phone jack or phone line and typically has anywhere between four to six wires.  The RJ-11 connects a device called a dial-up modem (analog modem) or a fax device to a telephone line. The connecting modem translates digital signals into analog form for transmission over phone lines, and the remote modem reverses the process.  Because signals were sent in both directions, both modems translated digital-to-analog signals and analog-to-digital signals. Keep in mind, before the widespread availability of DSL, cable, & fiber optic internet connections, dial-up connections were standard for practice internet access.  Even though dial-up modems are pretty much obsolete in the greater context of internet access, they are still very useful when it comes to sending data via a fax machine, assuming the dial-up modem has a fax capability of course.

RJ-11 Cable

Registered Jack 45 (RJ-45) Ethernet Connector

The RJ-45 connector is an 8-pin connection used for all types of copper wire based ethernet networking, including the most common types (fast ethernet & Gigabit ethernet).  The connector is is most commonly connected to the end of a Cat-5 cable, which is connected between a computer network card and a network device such as a network switch or router.  The following table lists the recommended cable grade for various types of wired ethernet. Using a cable grade lower than the one recommended for a particular ethernet connection speed can result in excessive transmission and reception errors or a reduction in network speed.

RJ-45 Cable
Ethernet Cable Grade & Supported Networks
CAT is short for “category”.
*Other types of 10G Ethernet use fiber optic cable.


Wireless networks are computer networks that are  not connected by cables of any kind. The use of a wireless network enables enterprises to avoid the costly process of introducing cables into buildings or as a connection between different equipment locations.  Wireless networking enables a computer, smartphone, tablet, or multifunctional peripheral (printer, scanner, copier, etc) to connect with other devices without data cables. The three types of wireless ethernet connections for the CompTIA IT Fundamentals exam you need to understand are:

  • Wireless Ethernet (Wi-Fi), explained in greater detail in later sections
  • Bluetooth
  • Near-Field Communication (NFC)

Bluetooth and NFC are considered to be short-range wireless networks.


Bluetooth is a wireless technology standard used for exchanging data between fixed and mobile devices over short distances using short wavelength UHF (ultra high frequency) radio waves in the industrial, scientific & medical radio bands, from 2.400 to 2.485 GHz, and building personal area networks (PANs).  Bluetooth can be used to do the following:

  • Connect to wireless speakers, mice, keyboards, printers, and game controllers
  • Transfer files between devices
  • Control home security or automation devices
  • Integrate your smartphone with your car’s audio or navigation system

The process of connecting two Bluetooth devices to each other requires the following settings:

  • Bluetooth must be enabled on both devices.  Bluetooth can be turned on or off on computers, tablets, and smartphones.
  • The computer, smartphone, or tablet must be discoverable.  Depending on the operating system and device, this option may be turned on automatically when you turn on Bluetooth.
  • The device must be paired.
Enabling Bluetooth

There are 3 Bluetooth power classes, but most Bluetooth devices use Class 2 radios.

Bluetooth Power/Distance Classes

Near-Field Communication (NFC)

Near-field communication is a set of communication protocols that enable 2 electronic devices, one of which is usually a portable device such as a smartphone, to establish communication by bringing them within 4 cm of each other.  NFC enables smartphones to be used for payment services such as Apple Pay, Samsung Pay, and others. NFC also enables file transfer between supported devices. To transfer files between smartphones with NFC, both smartphones must have NFC enabled and an NFC file transfer utility enabled, such as S Beam (Samsung smartphones) or Android Beam (Android smartphones).  Once that is enabled, simply tap the phones together to transfer files. NFC can also be used with compatible printers for tap-to-print capabilities.

Peripheral Devices

The rise of laptop computers with few or no internal upgrades available and the need to have peripherals that work with all types of computers, external peripheral devices have become very popular.  The IT Fundamentals exam focuses on the following peripheral devices:

  • USB
  • FireWire
  • Thunderbolt
  • Bluetooth
  • RF

Universal Serial Bus (USB)

USB is a plug-and-play interface that allows a computer to communicate with a peripheral and other devices.  USB ports can be used for input devices such as keyboards, mice, and scanners; storage devices such as flash drives, optical drives, and external hard drives; output devices such as printers, multifunction devices, and even displays; and adapters for both wired and wireless networks.  A single USB port (also known as a root hub) can connect to multiple devices when a USB hub is connected to the port.

Current USB Versions
*High-amperage USB 3.0 ports for charging tablets are marked in yellow.
**Also known as USB 3.1 Gen 1

Most computers today come loaded up with drivers, so if a USB device is plugged into a computer, in most cases the device is recognized automatically.  If the device is a storage device, the user might be prompted to select an action to take when the drive is connected. If the device is not recognized, then the user will be prompted to install a driver.


FireWire (also known as IEEE 1394) is a method of transferring information between digital devices, especially audio and video equipment.  FireWire comes in two versions: FireWire 400 which runs at up to 400Mbps and FireWire 800 (IEEE 1394b) which runs at up to 800Mbps. FireWire 800 uses a 9-pin connector and FireWire 400 uses either a 4-wire or 6-wire connector.  The FireWire 800 connection hosts only FireWire 800 devices, whereas the the Bilingual connector can host either FireWire 400 or FireWire 800 devices; just use the appropriate cable.

FireWire Cable


Thunderbolt is a high-speed peripheral connection standard originally introduced by Apple for its macOS desktop and laptop computers.  Thunderbolt has also been adopted by some manufacturers of computers and motherboards that use Microsoft Windows. Thunderbolt allows the connection of external peripherals to a computer. Thunderbolt 1 & 2 use the same connector as Mini DisplayPort (MDP), whereas Thunderbolt 3 re-uses the USB-C connector from USB.  Thunderbolt is also used for high-speed storage, including external drives, network attached storage (NAS), and Redundant Array of Independent Disks (RAID), as well as for high-resolution video. Thunderbolt also supports daisy-chained peripherals.  In Thunderbolt, a cable from the computer connects to the first device in the chain. The device has two Thunderbolt ports, so another device is connected to the second port and so on. If storage and display devices are mixed on a single Thunderbolt daisy chain, the display needs to be the last device.

Thunderbolt Versions
*The connectors are the same shape, but the cables are not interchangeable.
USB-A & Thunderbolt Cables

A docking device is a device that uses a single connector to the computer to provide several different types of peripheral connections.

Typical Docking Station


Bluetooth is a wireless technology used for exchanging data between fixed and mobile devices over short distances using short wavelength UHF radio waves.  A Bluetooth adapter can be plugged into a USB 2.0 or faster port to add Bluetooth support to a laptop or desktop computer as needed.

Radio Frequency (RF)

Radio frequency is a general term for wireless devices that do not use one of the established standards (Bluetooth or Wireless Ethernet).  The major devices that use proprietary RF interfacing are mice and keyboards that do not support Bluetooth. Most of these devices use dedicated transceivers that plug into a USB 2.0 or faster port.  If a wireless mouse and keyboard are bundled together, a single transceiver (combo of transmitter & receiver) is provided for both devices.

Graphic Device

Data output through graphic devices on computer systems is made possible through techniques that use video generation modules to display images.  Graphic device ports are used to connect the graphics processing unit (GPU) on a video card or built into the processor (CPU) to displays of various types, including flat panel LCD or LED monitors, LED or LCD HDTVs, and projectors.  When you see a computer’s port cluster or video card with 2 or more graphic device ports, you can connect at least 2 displays to the system.

Video Card Graphic Ports
Graphic Device Ports
*Powered adapters are available to enable connection to DVI or VGA.
**Mini DisplayPort supports all DisplayPort features.
***Mini HDMI port supports all HDMI features.

Video Graphics Array (VGA)

A VGA (or video graphics adapter) is a popular display that provides 640×480 resolution color display screens with a refresh rate of 60 Hz and 16 colors displayed at a time.  If the resolution is lowered to 320×200, 256 colors are shown. VGA utilizes analog signals, which means it is only capable of lower resolutions & lower quality display on screens. Because it is an analog standard, computers must convert digital video signals to analog before sending them through a VGA port to a display.  Because current displays are digital, the VGA signal must be converted back to digital before it can be displayed. This dual-conversion process can lead to display issues. Display resolution refers to the number of dots (horizontal & vertical) displayed on screen.  The greater the number of dots, the higher the resolution & the sharper and more detailed the display.

Digital Visual Interface (DVI)

DVI was designed to replace VGA while also being compatible with VGA signals.  It was developed to be an industry standard for transmitting digital video content to display devices at resolutions as high as 2560×1600.  Common devices that utilize the DVI connection are computer monitors & projectors. The DVI connector may have one of three names depending on the signals it supports:

  • DVI-A (analog only)
  • DVI-D (digital only)
  • DVI-I (both digital and analog)

High-Definition Multimedia Display (HDMI)

HDMI is a connector and cable capable of transmitting high-quality and high-bandwidth streams of audio and video between devices.  HDMI was originally developed for use with HDTVs, it is now a common feature on laptops, desktops, & monitors as well as HDTVs and HD projectors.  HDMI can carry both audio and video signals. HDMI is available in various versions, but older HDMI cables might not support advanced functions such as 3D or resolutions beyond 1080p.

DisplayPort (DP)

DisplayPort is a digital display interface primarily used to connect to a video source to a display device such as a computer monitor.  It can also be used to carry audio, USB and other forms of data. DisplayPort has similar resolution and audio/video features of HDMI, but with 2 major differences:

  • DisplayPort is a royalty-free video standard
  • DisplayPort 1.2 and later support daisy-chaining of displays

Mini DisplayPort (MiniDP or mDP)

The Mini DisplayPort is a miniaturized version of the DisplayPort audio-visual digital interface.