CompTIA Tech+ (FC0-U71): Peripheral Devices and Input/Output Interfaces

Plug-and-play means the operating system recognises a device the moment it is connected and loads a generic driver it already has, so the device works with no software installed by the user; driver installation means running the manufacturer's driver or software package so the operating system can use the device fully. A driver is the small program that lets the operating system talk to a particular piece of hardware.

Basic keyboards, mice, flash drives, external drives and most webcams and headsets are plug-and-play: the generic driver covers everything they do. More complex devices often work only partly with the generic driver. A graphics tablet is a good example: the generic driver may let the pen move the pointer like a mouse, yet pressure sensitivity and the programmable buttons do nothing until the maker's driver is installed. Multifunction devices behave the same way: a generic driver can cover the basic function while the extra functions, utilities and status reports arrive only with the manufacturer's package. When a device clearly communicates with the computer but some of its features are absent, suspect the driver before the hardware.

Installing a driver normally needs administrator rights. Plug-and-play works for any user because the generic driver is already part of the operating system, but adding the manufacturer's driver or utility changes the system, so the OS asks for an administrator. On a managed work computer, a standard user who lacks those rights asks IT (or uses the company's approved software portal) to install it. When the basic functions work, the hardware is fine; missing extra features point to the driver, not the device.

A firmware update is different from both: it replaces the software stored inside the device itself to fix bugs or add features. It is a maintenance step, not how a new device is installed.

A peripheral is any device connected to a computer to add input, output or storage, and installing one means connecting it, getting the right driver, then completing the few device-specific steps that make it usable. The table lists the objective's devices and the extra steps that commonly follow the physical connection.

Other steps that apply to many devices: updating the device's firmware, creating an account or pairing through the maker's phone app, granting permissions, and — for anything that joins the network — changing the default password (see the IP-based peripherals section).

The right display device is the one whose output matches where and how big the picture must be. A monitor is a desk-sized panel for one person's computer. A projector throws a large image onto a wall or screen from a laptop's video output, which suits classrooms and meeting rooms. A smart TV is a television with a network connection and built-in apps, so it can play online video by itself and accept casting or mirroring. A streaming media device — a stick or small box — plugs into a TV's HDMI port, joins the Wi-Fi network and supplies the streaming apps, so any screen with a free HDMI input gains apps and casting support.

Match the device to the room as well as the task. A projector reflects light off a wall or screen, so in a sunny or brightly lit space its picture looks faded; it suits dim classrooms, meeting rooms and home cinemas. A TV or monitor emits its own light and stays readable in daylight. When a screen must work on its own with no computer attached — for example a lobby or waiting-room screen showing a slideshow or video — a smart TV is the self-contained choice: an ordinary computer monitor has no apps or cast receiver of its own, and a streaming stick has no screen, so either one needs the other device (and the stick its own power lead).

Keep the direction of each device clear: displays, projectors and TVs are output devices, while cameras of any kind (webcams, document cameras) are input devices that capture an image and still need a screen to show it. Storage devices, whether a USB drive or a network file share, hold content but cannot play it on their own.

An IP-based peripheral is a device that connects to the network and gets its own IP address, so computers reach it over the network rather than through a cable to one PC; IP security cameras and network printers are the common examples. They are usually configured through a built-in web page: find the device's address (in the router's list of connected devices, on the device's display or in the maker's app), type that address into a browser, sign in and work through the settings.

The typical web-based configuration steps are:

1. Connect the device to the network (Ethernet, or Wi-Fi through the maker's setup app).
2. Find its IP address and open it in a web browser.
3. Sign in with the default credentials and immediately change the default administrator password — default passwords are published in manuals and online, so anyone on the network could take over the device until it is changed.
4. Give the device a stable address: reserve its address in the router (a DHCP reservation) or set a static IP, so bookmarks, apps and recorders keep finding it.
5. Update the firmware, then set the device's own options (camera recording and alerts, printer name and defaults).

The stable-address step matters because routers normally hand out addresses automatically with DHCP, and an address is only leased, not owned. After a power cut, for example, a network printer may come back with a different address, and every computer still pointing at the old one reports it offline even though the printer itself works. A DHCP reservation (or a static address) ties the device to one address so this cannot happen; the address is decided by the router's DHCP settings, not by anything stored on the device.

An uninterruptible power supply (UPS) is a battery unit placed between the wall outlet and equipment that takes over within milliseconds when mains power fails — fast enough that the equipment keeps running — keeping computers and network gear running for a few minutes so work can be saved and systems shut down cleanly. Many UPS units connect to the computer by USB so the OS can shut down automatically when the battery runs low. Compare it with its look-alikes:

Wearable devices — fitness bands, smartwatches — are worn on the body, track activity and health data such as steps and heart rate, and sync to a phone app, usually over Bluetooth. Connected exercise equipment — a smart treadmill, bike or rowing machine — records workouts too, but it is a machine you use, not something you wear; it typically joins Wi-Fi, pairs with heart-rate straps and needs an account and firmware updates. Medical devices for home use, such as blood-pressure cuffs, glucose monitors and pulse oximeters, often pair by Bluetooth with a phone app that shares readings with a clinician. Because they carry health data, set them up with the maker's official app, keep their firmware current and pair them only with your own devices.

RJ45 is the eight-pin modular plug on twisted-pair copper Ethernet cables, used on computers, routers and switches, and a single copper run is limited to about 100 meters. SFP (small form-factor pluggable) is a slot on switches and routers that accepts a swappable transceiver module, most often for fiber, which carries links over hundreds of meters to many kilometres — the choice for joining buildings.

Power over Ethernet (PoE) sends power along the same RJ45 cable, so a camera or access point needs no separate power supply. It adds power, not distance: a PoE run is still limited to about 100 meters.

Two tools build and check copper cables. A crimper presses an RJ45 plug's metal pins into the wires and locks the plug onto the cable — the tool for putting connectors on bulk cable. A cable tester then checks the finished cable: that each wire connects end to end in the right order. Do not confuse them with a punchdown tool, which seats wires into a patch panel or wall jack, or a toner probe, which traces which cable is which in a wall or bundle.

Wireless interfaces differ mainly in range and in whether devices talk directly or through a network. NFC (near-field communication) works only over a few centimetres and exchanges small amounts of data — tap-to-pay, transit cards, tapping to start pairing. Bluetooth links devices directly to each other over several metres after pairing, with no router — earbuds, headsets, speakers, keyboards, wearables. Proprietary radio frequency (RF) links, usually at 2.4 GHz, connect a wireless keyboard or mouse to the small USB receiver supplied in its box, so they work even on a computer with no Bluetooth. 802.11 (Wi-Fi) connects devices to a network through an access point or router over tens of metres.

Cellular (4G/5G) connects a phone to the carrier's network; it is not the link between a phone and a nearby accessory. The individual 802.11 standards and setting up a home Wi-Fi network are covered in the networking lesson for this domain.

Display ports carry the picture from a computer to a screen, and the key differences are whether the signal is analog or digital and whether it carries sound. VGA is the older 15-pin connector carrying analog video only. DVI is an older monitor port whose DVI-D form is digital-only (the DVI-I form also carries analog, which is why DVI-to-VGA adapters exist); it normally carries no audio. HDMI carries digital video and audio on one cable and is the standard connection on TVs and projectors (as inputs) and on game consoles and streaming devices (as outputs). DisplayPort is a digital computer-monitor interface that also carries video and audio, supports high resolutions and can daisy-chain monitors. USB-C can carry video too, but only on ports that support it (DisplayPort Alternate Mode, Thunderbolt or USB4).

Three facts decide most adapter choices:

• HDMI and DVI-D share the same digital video signal, so a simple HDMI-to-DVI cable connects them (picture only, since DVI normally carries no sound).
• Sound needs a port that carries audio. To send both picture and sound to a TV or projector over one cable, use HDMI; an adapter to VGA or DVI gives a picture with no sound.
• Not every USB-C port outputs video. A USB-C port without DisplayPort Alt Mode, Thunderbolt or USB4 support carries data and power only, and then no USB-C video adapter of any kind will help. Look for the DisplayPort or Thunderbolt symbol next to the port, or use another video port.

An adapter also needs a matching input on the other end: the target screen must actually have the port the adapter produces.

USB is the general-purpose connector family for peripherals, and its connector shapes tell you which end goes where. USB-A is the flat rectangular plug that goes into computers, chargers and hubs. USB-B is the squarish plug that goes into printers, scanners and some external devices, so a typical printer cable is USB-A to USB-B (smaller Mini-B and Micro-B variants appear on older phones and gadgets). USB-C is small, oval and reversible; it is used at both ends on modern laptops, phones and accessories and can carry data, power and — on supporting ports — video.

Thunderbolt is a high-speed interface that, since Thunderbolt 3, uses the USB-C connector shape. One Thunderbolt cable can carry fast data, video for one or more displays and power at the same time. That bandwidth is why Thunderbolt is used for demanding devices such as an external graphics card enclosure, or a dock that adds Ethernet, audio and several USB ports through one connection. USB-A, by contrast, is a data-and-power connector with no video, and HDMI and DisplayPort are video connectors that carry no general peripheral data.

Lightning is Apple's proprietary, small, flat, reversible 8-pin connector for charging and data on older iPhones, iPads and accessories. Apple moved the iPhone to USB-C starting with the iPhone 15, so newer models need a USB-C cable and older ones a Lightning cable.

Screen mirroring sends a live copy of a device's whole screen to a TV or projector, so whatever the device shows — any app, with or without a cast button — appears on the big screen; casting hands a media stream to the TV or streaming device, which then plays it by itself while the phone or laptop acts as a remote and stays free for other apps.

In short, mirroring suits anything that must appear exactly as it does on the sending device, while casting suits media playback where the sender should stay free. Playing content from an app that runs on the TV itself is a third option, separate from both, because the TV's own software then decides how it looks. On a computer with a wired or wireless second screen, you can also extend the desktop instead of duplicating it, which gives the presenter a separate screen.