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A CDE Definition

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(1) (powered USB) A USB port on a computer that can charge a portable device even when the computer is turned off, as long as it is plugged into the wall.

The Yellow USB
The yellow USB port is live for charging even when the computer is turned off.

(2) (PoweredUSB) A high-power USB interface from IBM that provides six amps at 5, 12 and 24-volts. Used for peripherals that need more than the standard USB maximum 500 milliamps, power is transferred in separate wires within the cable. See USB.

Sockets on the Host Side
The power socket is stacked above the standard USB socket, and PoweredUSB plugs insert into both cavities. Notice how sockets are keyed differently depending on voltage. The other side of the cable is typically permanently attached to the peripheral device.


(1) Short for "USB flash drive" or "USB port." See USB drive and USB port.

(2) (Universal Serial Bus) The most widely used hardware interface for attaching peripherals to a computer. There are at least two USB ports on laptops and four on desktop computers, while USB "hubs" provide more connections (see below). After appearing in 1997, USB became the standard for connecting keyboards, mice, printers and hard drives, eventually replacing the PC's serial and parallel ports and the Apple Desktop Bus on Macs (see serial port, parallel port and ADB).

Supporting 127 peripheral units on a single computer, devices can be plugged and unplugged while the computer is on, although a manual "eject" is required before removing. This "hot swappable" feature, combined with easy-to-reach ports on the front of the computer case, gave rise to the ubiquitous flash drive for transport (see USB drive). See PoweredUSB, USB device class, USB OTG, USB switch and USB toy.

USB Can Be Power Only
USB is also a power source for many small devices. This Chromecast streamer gets its DC power from a USB port (conveniently nearby in this photo). See Chromecast. (Image courtesy of Google Inc.)

                           Transfer Rate
 Version (Year)               (Mbps)

 USB 1.1 (1998)             1.5 & 12
  (1.5 Mbps slow channel
  for keyboards, mice, etc.)

 USB 2.0 Hi-Speed (2001)       480

 USB 3.0 SuperSpeed (2008)    4800
  (see USB 3.0)

 USB 3.1 (2014)               9600
  (see USB 3.1)

Type A and Type B Ports
All USB devices have sockets, and all the cables have plugs. Host sockets are Type A, and peripheral sockets are B, Mini-B or Micro-B. For expansion, hubs have a B or Mini-B socket to connect to the computer and several Type A sockets for devices (see USB hub).

USB Plug Configurations
With several type A sockets on every computer, USB cables have a Type A plug on one end and one of the B plugs on the other. There are also A-to-A extension cables. See Mini USB, Micro USB and USB OTG.

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Before/After Your Search Term
POWER8powerline adapter
PowerBookpowerline bridge
PowerBuilderpowerline Ethernet bridge
PowerCDpowerline network
powerchippowerline networking
powered eSATApowerline USB
powered EthernetPowerMac
powered speakerPowermat
Powered USBPowerOpen

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