A USB decoration is a decorative device that uses the Universal Serial Bus

Universal Serial Bus

USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 (USB) connector for electrical power, and sometimes the protocol, on a computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

 or other host. In addition, some lightweight devices (e.g. a small lamp on a gooseneck stalk) use the USB connector itself for mechanical support.

History

Decorative computer peripherals have been around for a long time; in the days of CPU front panel

Front panel

A front panel was used on early electronic computers to display and allow the alteration of the state of the machine's internal registers and memory. The front panel usually consisted of arrays of indicator lamps, toggle switches, and push buttons mounted on a sheet metal face plate...

s, computer hackers

Hacker (computer security)

In computer security and everyday language, a hacker is someone who breaks into computers and computer networks. Hackers may be motivated by a multitude of reasons, including profit, protest, or because of the challenge...

 would sometimes use them for entertaining or amusing "Blinkenlights

Blinkenlights

Blinkenlights is a hacker's neologism for diagnostic lights on old mainframe computers and modern network hardware.The Jargon File provides the following etymology:...

" displays. Today, USB-powered decorations are the most prominently seen examples, since the popularity of USB

Universal Serial Bus

USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....

 lets them operate on most modern computers.

USB Interface

Many USB decorations do not use the communications features of the USB bus, or fully comply with USB standard power discipline. This can interfere with the purposes for which the USB bus was designed, especially if the device suddenly attempts to draw the full 500mA

Ampere

The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...

 of power nominally available. The default power consumption is only 100mA, which should not impact the computer's PSU

Power supply

A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...

 if a device is suddenly connected without identifying itself first. A newly-connected device is supposed to then use the USB protocol to communicate a request for more DC power, if needed.

Often, several decorations are connected to a single USB hub

USB hub

A USB hub is a device that expands a single USB port into several so that there are more ports available to connect devices to a host system.USB hubs are often built into equipment such as computers, keyboards, monitors, or printers...

, which is limited to 400mA if it has no external power connection and is drawing all its power from a host computer . With each device drawing 100mA, it is therefore only possible to run four low-power decorations.

If instead a USB hub has an external power adapter, it may be able to support much higher power loads. In many cases, the powered hub may not even need to be connected to a computer host, but can serve as a stand-alone power source for USB decorations that need only DC power.

Decorative usage

USB decorations may have no useful functionality other than aesthetic ornamentation. For example, lights, lighted cables, displays, miniature disco balls, aquariums, terrariums, waterfalls and pole dancers are all available in USB-powered versions.

Arguably, there are many USB-based decorations embedded in existing products—keyboard

Computer keyboard

In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...

s with impractical backlighting (such as ones that only turn on while pressing a key, and ones that flash to the beat of a song), mice

Mouse (computing)

In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...

 that (when the computer is turned off) turn on/off their light to a pre-programmed beat, or printers that show random quotations on LCD screens when not in use.

A similar concept exists in the form of decorations that are powered by car adapter plugs. USB adapters for automobiles (and built-in USB ports in newer models) can also power USB decorations. Some USB devices can even be jury-rigged to work on 12 volts with a simple resistor.

Functional semi-decorations

Some USB decorations have a non-passive and at least nominal practical purpose. Nightlight

Nightlight

A nightlight is a small light fixture, often electrical, placed for comfort or convenience in dark areas or areas that become dark at certain times, such as in an emergency...

s, cooling fans, typing speedometers, a beverage chiller, and nodding dogs that guard internet connections are all examples of USB semi-decorations.

Flash drives may similarly be themed for aesthetic or amusement value. Such devices can be viewed anthropologically as pocket-sized versions of the "decorated shed" architecture celebrated by Robert Venturi

Robert Venturi

Robert Charles Venturi, Jr. is an American architect, founding principal of the firm Venturi, Scott Brown and Associates, and one of the major figures in the architecture of the twentieth century...

in his influential book, Learning from Las Vegas: the Forgotten Symbolism of Architectural Form.

Although these functional devices are not pure USB decorations, they are still have prominent decorative aspects. Usually these types of devices are simple modifications of ordinary designs, with most or all of the power used for the main function, not for the decoration.