Lis chaque section en anglais. Le resume en francais ("En bref") est juste un filet de securite : essaie de comprendre en anglais d'abord.
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This chapter explains wired and wireless connectivity: how to connect devices to the right ports on a computer. Some ports can be tricky to recognize at first, but every IT professional should be able to identify the common ports used today.
A port is a connector on a motherboard, or on a separate adapter, that lets a device connect to a computer. Ports can be found all around a computer case or a mobile device.
A connector on a motherboard or on a separate adapter that lets a device connect to a computer.
On a separate adapter (expansion card).
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Mouse ports and keyboard ports were traditionally 6-pin mini-DIN ports, also called PS/2 ports. The mini-DIN port is keyed, so the cable can be inserted only one way.
Today, USB ports are more commonly used for mouse and keyboard connectivity, but some gaming motherboards still have a mini-DIN port.
Manufacturers color-code these ports: green for the mouse port and purple for the keyboard port. They may also put a small picture of a mouse or keyboard next to each connector.
Mouse = green, keyboard = purple.
The cable can only be inserted in one correct orientation.
USB.
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Some ports/cables can be used for multiple types of devices: USB 2.0, USB 3.x, USB4, USB-C, Thunderbolt, and Lightning. These are called multipurpose ports. USB is the one most people know, but Thunderbolt and Lightning are multipurpose ports too.
USB stands for Universal Serial Bus. It is one of the most popular ports on modern devices. A single USB port allows up to 127 connected devices, transmitting at speeds up to 40 Gb/s (40 billion bits per second). Many device types connect through USB: printers, scanners, mice, keyboards, joysticks, optical drives, game pads, cameras, modems, speakers, IP phones, video phones, data gloves, and digitizers. Extra USB ports can sometimes be found on the front of a PC case or the side of a mobile device.
USB ports come in several versions: USB 1.0/1.1, USB 2.0 (also called Hi-Speed), USB 3.0 (also called 3.2 Gen 1 SuperSpeed and 3.2 Gen 2 SuperSpeed+), and USB4.x. Each version has its own maximum speed - see the reference table below for the full list, including port colors.
TECH TIP - Understanding USB speed through documentation: not every USB port has a clear speed label. The most reliable way to find out what a port supports is to check the technical specifications of the computer or motherboard.
USB Power Delivery (USB-PD): since USB 2.0, USB ports have been able to supply 5V at 500mA (2.5 watts) of power to a connected device. The newest standard, USB Power Delivery (PD or USB-PD), can supply up to 48V at 5A - up to 240 watts. USB-PD actually has several power levels: 10, 18, 36, 60, 100, 140, and 240 watts. Every USB4 connection supports charging a USB device.
| Port type / alternate name | Maximum transmission speed | Port color | Cable type/length and alternate name |
|---|---|---|---|
| USB 1.x | 1.5 Mb/s and 12 Mb/s | Usually white | 9.8" (3 m) Type-A; 1.0 low speed / 1.1 full speed |
| USB 2.0 | 480 Mb/s | Black | 9.8" (3 m) Type-A, Hi-Speed |
| USB 3.0 | 5 Gb/s | Blue | 9.8" (3 m) Type-A or Type-C, SuperSpeed |
| USB 3.1 Gen 1 | 5 Gb/s | Blue | 9.8" (3 m) Type-A or Type-C, SuperSpeed |
| USB 3.1 Gen 2 | 10 Gb/s | Teal | 9.8" (3 m) Type-C, SuperSpeed+ |
| USB 3.2 Gen 1 (1x1 = 1 lane / 1x2 = 2 lanes) | 5 Gb/s and 10 Gb/s | Red | 9.8" (3 m) Type-C, SuperSpeed USB 5Gbps / SuperSpeed USB 10Gbps |
| USB 3.2 Gen 2 (2x1 = 1 lane / 2x2 = 2 lanes) | 10 Gb/s and 20 Gb/s | Red | 9.8" (3 m) Type-C, SuperSpeed USB 10Gbps / SuperSpeed USB 20Gbps |
| USB4 Gen 2 (2 lanes) | 20 Gb/s | N/A | 9.8" (3 m) Type-C |
| USB4 Gen 3 (2 lanes) | 40 Gb/s | N/A | 9.8" (3 m) Type-C |
| USB sleep-and-charge | N/A | Yellow, orange, or red | N/A |
Up to 127 devices.
USB Power Delivery, a standard that can supply up to 48V at 5A, or 240 watts.
Blue.
Check the technical documentation/specifications of the computer or motherboard.
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Every USB standard has a maximum recommended cable length (see Table 2.1). Cables can be made longer than the standard, but they may not work as reliably. An active USB extension cable (repeater cable) or a powered USB hub can help reach farther distances.
If a USB port is providing power to a device, the maximum cable length becomes shorter. For example, a USB 2.0 PD device should use a cable shorter than 13 feet (4 m); a USB 3.1 PD device using a USB Type-C cable should use a cable shorter than 3.3 feet (1 m). A PD device requires a Type-C cable, but not every Type-C port or cable supports PD.
Older USB ports are known as USB Type-A and USB Type-B. A USB printer cable, for example, has a Type-A male connector on one end (for the computer) and a Type-B male connector on the other end (for the printer). The port on the computer is a Type-A port.
USB Type-C (USB-C) is the newest connector and will eventually replace Type-A and Type-B. An adapter can be used to connect an older device to a Type-C port. Many USB 3.0 ports already use the Type-C design, although some still use the traditional Type-A connector. USB 3.1 ports and newer versions need a Type-C cable to reach their full speed and features. USB-C can carry audio, video, and data, and its connector can be inserted into the port with either side facing up (it is reversible).
Two smaller USB ports used on portable devices (hubs, external hard drives, digital cameras, smartphones) are miniUSB and microUSB. There are several types: mini-A, mini-AB, micro-B, and micro-AB. The mini-AB and micro-AB ports each accept either a mini-A/micro-A cable end or a mini-B/micro-B cable end.
A USB port can connect to multiple devices through a USB hub. Hubs work in two power modes: self-powered (also called a powered hub - it has its own external power supply, sometimes with a toggle switch that must be set to provide power) and bus-powered (no external power supply attached). After testing the USB devices connected to a self-powered hub, you can disconnect the hub's power supply and retest the devices; if they all still work fine without it, it is safe to leave it disconnected.
USB cabling rules: up to 5 hubs can be chained together, for a total maximum distance of 88.5 feet (27 meters), with up to 127 devices connected across those hubs. The maximum distance between two USB hubs is 16.4 feet (5 m) for high-speed devices and 9.8 feet (3 m) for low-speed devices.
USB ports have always been able to provide power to unpowered devices, such as flash drives. A charging USB port is specifically designed to provide power and charge attached devices (not every USB device can be powered on while it is charging). A sleep-and-charge USB port keeps providing charging power to a device even when the computer itself is powered off.
Safely removing USB devices: never simply unplug a USB device. On Windows, click Safely Remove Hardware and Eject Media in the notification area, then select the device to remove. On a Mac, right-click the device's desktop icon and select Eject, or drag the icon to the trash. On Ubuntu Linux, locate the device in Files/File Explorer and click the small eject icon, or right-click and select Eject. This helps prevent data loss and makes sure the device disconnects properly.
USB converters have become popular for modern laptops and tablets that are thin and lightweight and don't include many traditional ports. Whether you need to connect to an Ethernet network, hook up an external monitor, or use a different connector type, a USB converter (such as a USB-to-Ethernet converter) provides a flexible solution.
Installing extra USB ports: many motherboards support adding two or more USB ports through a cable that attaches to an internal USB connector on the motherboard, called a USB header. The term "header" simply means a set of motherboard pins reserved for a specific purpose - USB, SATA, eSATA, RGB LEDs (lights), and TPM (Trusted Platform Module) all commonly have their own headers. Header-based ports mount into an expansion-slot opening, but they don't have a card that plugs into an expansion slot. Even when a motherboard has these header pins, the actual ports and cable assembly sometimes must be purchased separately.