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Encyclopedia > Universal Serial Bus
USB
Universal Serial Bus

Original USB Logo
Year created: January 1996

Width: 1 bit
Number of devices: 127 per host controller
Capacity 12 or 480 Mbit/s
Style: Serial
Hotplugging? Yes
External? Yes
A USB Series “A” plug, the most common USB plug
A USB Series “A” plug, the most common USB plug
The USB "trident" Icon
The USB "trident" Icon

Universal Serial Bus (USB) is a serial bus standard to interface devices. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). Other convenient features include providing power to low-consumption devices without the need for an external power supply and allowing many devices to be used without requiring manufacturer specific, individual device drivers to be installed. USB can mean: Universal Serial Bus, a computer bus standard upper sideband, an amplitude modulation transmission method by radio Unified S-band in communications satellites ultrasound-guided biopsy in oncology Uniwersytet Stefana Batorego (Stefan Batory University; now Vilnius University) US Bancorp (NYSE: USB) financial services holding company This is a... Note: USB may also mean upper sideband in radio. ... Image File history File links This is a lossless scalable vector image. ... This article is about the unit of information. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... Image File history File links Metadata Size of this preview: 626 × 600 pixelsFull resolution‎ (1,654 × 1,585 pixels, file size: 320 KB, MIME type: image/jpeg) USB plug type A Photographer: Andreas Frank, Munich, Germany Date: 2005-02-19 File historyClick on a date/time to view the file... Image File history File links Metadata Size of this preview: 626 × 600 pixelsFull resolution‎ (1,654 × 1,585 pixels, file size: 320 KB, MIME type: image/jpeg) USB plug type A Photographer: Andreas Frank, Munich, Germany Date: 2005-02-19 File historyClick on a date/time to view the file... Image File history File links USB_Icon. ... Image File history File links USB_Icon. ... In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... An electrical connector is a conductive device for joining electrical circuits together. ... Plug and Play is a term used in the computer field to describe a computers ability to have new devices, normally peripherals, added to it without having to restart the computer. ... Reboot, in computing is either a hard reboot (cold boot) or soft reboot (warm boot) of a computer. ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ...


USB is intended to help retire all legacy varieties of serial and parallel ports. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, and flash drives. For many of those devices USB has become the standard connection method. USB is also used extensively to connect non-networked printers; USB simplifies connecting several printers to one computer. USB lock software can lock out memory devices and still allow other USB peripherals to function. USB was originally designed for personal computers, but it has become commonplace on other devices such as PDAs and video game consoles. In 2004, there were about 1 billion USB devices in the world.[1] A male DE-9 connector used for a serial port on a PC style computer. ... This article is about the Centronics style port. ... For an account of the words periphery and peripheral as they are used in biology, sociology, politics, computer hardware, and other fields, see the periphery disambiguation page. ... Operating a mechanical 1: Pulling the mouse turns the ball. ... A 104-key PC US English QWERTY keyboard layout The Dvorak Simplified Keyboard layout A standard Hebrew keyboard showing both Hebrew and QWERTY. A computer keyboard is a peripheral partially modelled after the typewriter keyboard. ... User with Treo (PDA with smartphone functionality) Personal digital assistants (PDAs) are handheld computers, but have become much more versatile over the years. ... This article does not cite any references or sources. ... For other uses, see Joystick (disambiguation). ... In computing, a scanner is a device that analyzes images, printed text, or handwriting, or an object (such as an ornament) and converts it to a digital image. ... Look up digital camera in Wiktionary, the free dictionary. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. ... JumpDrive redirects here. ... Game console redirects here. ...


The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards body incorporating leading companies from the computer and electronics industries. Notable members have included Agere, Apple Inc., Hewlett-Packard, Intel, NEC, and Microsoft. The USB Implementers Forum, USB-IF, is a non-profit organisation to promote and support the Universal Serial Bus. ... Agere Systems Inc. ... Apple Inc. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... NEC Corporation (Jp. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ...

Contents

History

The USB 1.0 specification was introduced in November 1995. USB was promoted by Intel (UHCI and open software stack), Microsoft (Windows software stack), Philips (Hub, USB-Audio), and US Robotics. Originally USB was intended to replace the multitude of connectors at the back of PCs, as well as to simplify software configuration of communication devices. USB was also the primary connector on the original Apple iMac introduced 6 May 1998, including the connector for its new keyboard and mouse[2]. USB 1.1 came out in September 1998 to help rectify the adoption problems that occurred with earlier iterations of USB.[3] Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... U.S. Robotics (popularly nicknamed USR), based in Schaumburg, Illinois and founded in 1976, is a company that makes computer modems and related technologies. ... is the 126th day of the year (127th in leap years) in the Gregorian calendar. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ...


As of 2008, the USB specification is at version 2.0 (with revisions). Hewlett-Packard, Intel, Lucent (now Alcatel-Lucent), Microsoft, NEC, and Philips jointly led the initiative to develop a higher data transfer rate than the 1.1 specification. The USB 2.0 specification was released in April 2000 and was standardized by the USB-IF at the end of 2001. Equipment conforming with any version of the standard will also work with devices designed to any previous specification (known as backward compatibility). 2008 (MMVIII) will be a leap year starting on Tuesday of the Gregorian calendar. ... In technology, especially computing (irrespective of platform), a product is said to be backward compatible (or upward compatible) when it is able to take the place of an older product, by interoperating with other products that were designed for the older product. ...


Smaller USB plugs and receptacles for use in handheld and mobile devices, called Mini-B, were added to USB specification in the first engineering change notice. A new variant of smaller USB plugs and receptacles, Micro-USB, was announced by the USB Implementers Forum on January 4, 2007.[4] is the 4th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...


Overview

A conventional USB hub
A conventional USB hub

A USB system has an asymmetric design, consisting of a host, a multitude of downstream USB ports, and multiple peripheral devices connected in a tiered-star topology. Additional USB hubs may be included in the tiers, allowing branching into a tree structure, subject to a limit of 5 levels of tiers. USB host may have multiple host controllers and each host controller may provide one or more USB ports. Up to 127 devices, including the hub devices, may be connected to a single host controller. USB hub. ... A USB hub A USB hub is a hub device that allows many USB devices to be connected to a single USB port. ... Sphere symmetry group o. ... In computer hardware, a peripheral device is any device attached to a computer in order to expand its functionality. ... A USB hub A USB hub is a hub device that allows many USB devices to be connected to a single USB port. ...


USB devices are linked in series through hubs. There always exists one hub known as the root hub, which is built-in to the host controller. So-called "sharing hubs" also exist; allowing multiple computers to access the same peripheral device(s), either switching access between PCs automatically or manually. They are popular in small-office environments. In network terms they converge rather than diverge branches.


A single physical USB device may consist of several logical sub-devices that are referred to as device functions, because each individual device may provide several functions, such as a webcam (video device function) with a built-in microphone (audio device function). A typical webcam Webcams are small cameras, (usually, though not always, video cameras) whose images can be accessed using the World Wide Web, instant messaging, or a PC video conferencing application. ...

USB endpoints actually reside on the connected device: the channels to the host are referred to as pipes
USB endpoints actually reside on the connected device: the channels to the host are referred to as pipes

USB device communication is based on pipes (logical channels). Pipes are connections from the host controller to a logical entity on the device named an endpoint. The term endpoint is also occasionally used to refer to the pipe. A USB device can have up to 32 active pipes, 16 into the host controller and 16 out of the controller. Each endpoint can transfer data in one direction only, either into or out of the device, so each pipe is uni-directional. Endpoints are grouped into interfaces and each interface is associated with a single device function. An exception to this is endpoint zero, which is used for device configuration and which is not associated with any interface. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... An endpoint or end point is a mark of termination or completion. ...


When a new USB device is connected to a USB host, the USB device enumeration process is started. The enumeration process first sends a reset signal to the USB device. The speed of the USB device is determined during the reset signaling. After reset, USB device setup information is read from the device by the host and the device is assigned a unique host-controller specific 7-bit address. If the device is supported by the host, the device drivers needed for communicating with the device are loaded and the device is set to configured state. If the USB host is restarted, the enumeration process is repeated for all connected devices.


The host controller polls the bus for traffic, usually in a round-robin fashion, so no USB device can transfer any data on the bus without an explicit request from the host controller. Round-robin is one of the simplest scheduling algorithms for processes in an operating system, which assigns time slices to each process in equal portions and in order, handling all processes as having the same priority. ...


Host controllers

The computer hardware that contains the host controller and the root hub has an interface geared toward the programmer which is called Host Controller Device (HCD) and is defined by the hardware implementer. Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. ...


In the version 1.x age, there were two competing HCD implementations, Open Host Controller Interface (OHCI) and Universal Host Controller Interface (UHCI). OHCI was developed by Compaq, Microsoft and National Semiconductor; UHCI was by Intel. Open Host Controller Interface, or OHCI, are two open standards that allows a computer host to interact with FireWire and USB devices. ... A host controller interface is a register level interface which allows a host controller for USB or FireWire to communicate with the operating system of a personal computer. ... Compaq Computer Corporation is an American personal computer company founded in 1982, and now a brand name of Hewlett-Packard. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... Categories: Electronics companies of the United States | Companies based in California | Corporation stubs ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ...

A typical USB connector.

VIA Technologies licensed the UHCI standard from Intel; all other chipset implementers use OHCI. UHCI is more software-driven, making UHCI slightly more processor-intensive than OHCI but cheaper to implement. The dueling implementations forced operating system vendors and hardware vendors to develop and test on both implementations which increased cost. VIA Technologies logo VIA Technologies is a Taiwanese manufacturer of integrated circuits, mainly motherboard chipsets, CPUs, and memory, and is part of the Formosa Plastics Group. ...


HCD standards are out of the USB specification's scope, and the USB specification does not specify any HCD interfaces. In other words, USB defines the format of data transfer through the port, but not the system by which the USB hardware communicates with the computer it sits in.


During the design phase of USB 2.0 the USB-IF insisted on only one implementation. The USB 2.0 HCD implementation is called the Enhanced Host Controller Interface (EHCI). Only EHCI can support hi-speed transfers. Most of PCI-based EHCI controllers contain other HCD implementations called 'companion host controller' to support Full Speed and Low Speed devices. The virtual HCD on Intel and VIA EHCI controllers are UHCI. All other vendors use virtual OHCI controllers.


Device classes

Devices that attach to the bus can be full-custom devices requiring a full-custom device driver to be used, or may belong to a device class. These classes define an expected behavior in terms of device and interface descriptors so that the same device driver may be used for any device that claims to be a member of a certain class. An operating system is supposed to implement all device classes so as to provide generic drivers for any USB device. Device classes are decided upon by the Device Working Group of the USB Implementers Forum. An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ...


Device classes include:[5]

Class Usage Description Examples
00h Device Unspecifiedclass 0 (Device class is unspecified. Interface descriptors are used for determining the required drivers.)
01h Interface Audio speaker, microphone, sound card
02h Both Communications and CDC Control ethernet adapter, modem, serial port adapter
03h Interface Human Interface Device (HID) keyboard, mouse, joystick
05h Interface Physical Interface Device (PID) force feedback joystick
06h Interface Image Digital Camera (Most cameras function as Mass Storage for direct access to storage media).
07h Interface Printer laser printer, Inkjet printer
08h Interface Mass Storage USB flash drive, memory card reader, digital audio player
09h Device USB hub full speed hub, hi-speed hub
0Ah Interface CDC-Data (This class is used together with class 02h - Communications and CDC Control.)
0Bh Interface Smart Card USB smart card reader
0Dh Interface Content Security -
0Eh Interface Video webcam
0Fh Interface Personal Healthcare -
DCh Both Diagnostic Device USB compliance testing device
E0h Interface Wireless Controller Wi-Fi adapter, Bluetooth adapter
EFh Both Miscellaneous ActiveSync device
FEh Interface Application Specific IrDA Bridge
FFh Both Vendor Specific (This class code indicates that the device needs vendor specific drivers.)

Note class 0: Use class information in the Interface Descriptors. This base class is defined to be used in Device Descriptors to indicate that class information should be determined from the Interface Descriptors in the device. For the Marty Friedman album, see Loudspeaker (album) An inexpensive low fidelity 3. ... Microphones redirects here. ... A sound card (also known as an audio card) is a computer expansion card that can input and output sound under control of computer programs. ... USB communications device class (or USB CDC) is a composite Universal Serial Bus device class. ... A network card, network adapter or NIC (network interface controller) is a piece of computer hardware designed to allow computers to communicate over a computer network. ... For other uses, see Modem (disambiguation). ... A male DE-9 connector used for a serial port on a PC style computer. ... The USB human interface device class (USB HID class) is a USB device class that describes human interface devices such as computer keyboards, computer mice, game controllers, and alphanumeric display devices. ... Keyboard redirects here. ... A contemporary computer mouse, with the most common standard features: two buttons and a scroll wheel. ... Look up digital camera in Wiktionary, the free dictionary. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. ... 1993 Apple LaserWriter Pro 630 laser printer A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. ... An Epson inkjet printer Inkjet printers operate by propelling variably-sized droplets of liquid or molten material (ink) onto almost any medium. ... The USB mass storage device class (USB MSC) is a set of computing communications protocols defined by the USB Implementers Forum that run on the Universal Serial Bus. ... JumpDrive redirects here. ... Four major types of memory cards (from left to right: CompactFlash, Memory Stick, Secure Digital, and xD. A memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, handheld and Mobile computers, telephones, music players, video game consoles, and other... A card reader is a device used for communication with a smart card or a flash memory card. ... Apple iPod nano (third-generation), a best-selling flash-based player An embedded hard drive-based player (Creative ZEN Vision:M) An MP3 CD player (Philips Expanium) More commonly referred to as an MP3 player, a digital audio player (DAP) is a portable consumer electronics device that stores, organizes and... A USB hub A USB hub is a hub device that allows many USB devices to be connected to a single USB port. ... Smart card used for health insurance in France. ... The USB video device class (also USB video class or UVC) is a USB device class that describes devices capable of streaming video like webcams, digital camcorders, analog video converters, television tuners, and still-image cameras. ... A typical webcam Webcams are small cameras, (usually, though not always, video cameras) whose images can be accessed using the World Wide Web, instant messaging, or a PC video conferencing application. ... For other uses, see Wireless (disambiguation). ... Wi-Fi (IPA: ) is the common name for a popular wireless technology used in home networks, mobile phones, video games and more. ... Bluetooth logo This article is about the electronic protocol named after Harald Bluetooth Gormson. ... ActiveSync is a synchronisation program developed by Microsoft Corporation. ... This article is about an Infrared communications protocol. ...


USB mass-storage

A flash drive, a typical USB mass-storage device.

USB implements connections to storage devices using a set of standards called the USB mass storage device class (referred to as MSC or UMS). This was initially intended for traditional magnetic and optical drives, but has been extended to support a wide variety of devices, particularly flash drives. This generality is because many systems can be controlled with the familiar idiom of file manipulation within directories (The process of making a novel device look like a familiar device is also known as extension). Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... JumpDrive redirects here. ... The USB mass storage device class (USB MSC) is a set of computing communications protocols defined by the USB Implementers Forum that run on the Universal Serial Bus. ... A USB drive, shown with a 24 mm US quarter coin for scale. ...


Though most computers are capable of booting off USB Mass Storage devices, USB is not intended to be a primary bus for a computer's internal storage: buses such as ATA (IDE), Serial ATA (SATA), and SCSI fulfill that role. However, USB has one important advantage in that it is possible to install and remove devices without opening the computer case, making it useful for external drives. Originally conceived and still used today for optical storage devices (CD-RW drives, DVD drives, etc.), a number of manufacturers offer external portable USB hard drives, or empty enclosures for drives, that offer performance comparable to internal drives. These external drives usually contain a translating device that interfaces a drive of conventional technology (IDE, ATA, SATA, ATAPI, or even SCSI) to a USB port. Functionally, the drive appears to the user just like another internal drive. Other competing standards that allow for external connectivity are eSATA and FireWire. ATA cables: 40 wire ribbon cable top, 80 wire ribbon cable bottom Advanced Technology Attachment (ATA) is a standard interface for connecting storage devices such as hard disks and CD-ROM drives inside personal computers. ... A SATA power connector. ... Scuzzy redirects here. ... Compact Disc ReWritable (CD-RW) is a rewritable optical disc format. ... DVD (also known as Digital Versatile Disc or Digital Video Disc - see Etymology) is a popular optical disc storage media format. ... Manufacturing is the transformation of raw materials into finished goods for sale, or intermediate processes involving the production or finishing of semi-manufactures. ... A SATA power connector. ... The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ...


Human-interface devices (HIDs)

Mice and keyboards are frequently fitted with USB connectors, but because most PC motherboards still retain PS/2 connectors for the keyboard and mouse as of 2007, they are often supplied with a small USB-to-PS/2 adaptor, allowing usage with either USB or PS/2 interface. There is no logic inside these adaptors: they make use of the fact that such HID interfaces are equipped with controllers that are capable of serving both the USB and the PS/2 protocol, and automatically detect which type of port they are plugged into. Joysticks, keypads, tablets and other human-interface devices are also progressively migrating from MIDI, PC game port, and PS/2 connectors to USB. Not to be confused with PlayStation 2. ... 2007 is a common year starting on Monday of the Gregorian calendar. ... An electronic circuit is an electrical circuit that also contains active electronic devices such as transistors or vacuum tubes. ... Musical Instrument Digital Interface, or MIDI, is a system designed to transmit information between electronic musical instruments. ... A PCI based soundcard with a DA-15 connector The game port is the traditional connection for video game input devices on an x86-based PCs. ...


Apple Macintosh computers have been using USB exclusively for all external wired mice and keyboards since January 1999 (Powerbooks used ADB keyboards until 2005). The original iMac raised public awareness of USB considerably in August 1998, as it discarded legacy ports to use only USB. PCs had USB ports prior to the iMac's introduction, but they were included with a full complement of traditional ports which limited USB's adoption. The iMac's influence can be seen in the number of USB peripherals with matching translucent, colored plastic enclosures that were available in the late '90s and early '00s. The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... The PowerBook was a line of Macintosh laptop computers that was designed, manufactured and sold by Apple Computer, Inc. ... Early ADB device Apple Desktop Bus (or ADB) is an obsolete bit-serial bus for connecting low-speed devices to computers. ... The original Bondi Blue iMac G3 was introduced in 1998. ...


USB signalling

USB supports three data rates: In telecommunication, data signaling rate (DSR) is the aggregate rate at which data pass a point in the transmission path of a data transmission system. ...

  • A Low Speed (1.1, 2.0) rate of 1.5 Mbit/s (187.5 kB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.
  • A Full Speed (1.1, 2.0) rate of 12 Mbit/s (1.5 MB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed.
  • A Hi-Speed (2.0) rate of 480 Mbit/s (60 MB/s).

Experimental data rate: A megabit per second (mbps or mbit/s) is a unit of data transmission equal to 1,000 kilobits per second or 1,000,000 bits per second. ... A kilobyte (derived from the SI prefix kilo-, meaning 1,000) is a unit of information or computer storage equal to either 1,000 bytes or 1,024 bytes (210), depending on context. ... This article is about a unit of data. ... Isochronous means having an equal time difference or occurring simultaneously. ... In telecommunication, data signaling rate (DSR) is the aggregate rate at which data pass a point in the transmission path of a data transmission system. ...

  • A Super-Speed (3.0) rate of 4.8 Gbit/s (600 MB/s). The USB 3.0 specification will be released by Intel and its partners in mid 2008 according to early reports from CNET news. According to Intel, bus speeds will be 10 times faster than USB 2.0 due to the inclusion of a fiber optic link that works with traditional copper connectors. Products using the 3.0 specification are likely to arrive in 2009 or 2010.

USB signals are transmitted on a twisted pair data cable with 90Ω ±15% impedance,[6] labeled D+ and D−. These collectively use half-duplex differential signaling to combat the effects of electromagnetic noise on longer lines. D+ and D− usually operate together; they are not separate simplex connections. Transmitted signal levels are 0.0–0.3 volts for low and 2.8–3.6 volts for high in Full Speed and Low Speed modes, and ±400mV in High Speed (HS) mode. In FS mode the cable wires are not terminated, but the HS mode has termination of 45Ω to ground, or 90Ω differential to match the data cable impedance. CNET Networks, Inc. ... For other uses, see Copper (disambiguation). ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... A multimeter can be used to measure resistance in ohms. ... In telecommunications, duplex means two-way when referring to communications channels. ... It has been suggested that this article or section be merged into Low voltage differential signaling. ... A simplex communication system is one where all signals flow in one direction. ... Josephson junction array chip developed by NIST as a standard volt. ... Josephson junction array chip developed by NIST as a standard volt. ...


USB uses a special protocol to negotiate the High Speed mode called "chirping". In simplified terms, a device that is HS capable always connects as an FS device first, but after receiving a USB RESET (both D+ and D- are driven LOW by host) it tries to pull the D- line high. If the host (or hub) is also HS capable, it returns alternating signals on D- and D+ lines letting the device know that the tier will operate at High Speed.


Clock tolerance is 480.00 Mbit/s ±500ppm, 12.000 Mbit/s ±2500ppm, 1.50 Mbit/s ±15000ppm. Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ...


The USB standard uses the NRZI system to encode data, and uses "bit stuffing" by always injecting one artificial "zero" bit if the stream of data contains six consecutive "ones" before converting the bit stream to NRZI. In data transmission and telecommunication, bit stuffing (also known -- uncommonly -- as positive justification) is the insertion of noninformation bits into data. ...


Though Hi-Speed devices are commonly referred to as "USB 2.0" and advertised as "up to 480 Mbit/s", not all USB 2.0 devices are Hi-Speed. The USB-IF certifies devices and provides licenses to use special marketing logos for either "Basic-Speed" (low and full) or Hi-Speed after passing a compliance test and paying a licensing fee. All devices are tested according to the latest spec, so recently-compliant Low-Speed devices are also 2.0 devices. The USB Implementers Forum, USB-IF, is a non-profit organisation to promote and support the Universal Serial Bus. ...


The actual throughput currently (2006) attained with real devices is about two thirds of the maximum theoretical bulk data transfer rate of 53.248 MB/s. Typical hi-speed USB devices operate at lower speeds, often about 3 MB/s overall, sometimes up to 10-20 MB/s[7]. 2006 is a common year starting on Sunday of the Gregorian calendar. ...


USB connector properties

Series "A" plug and receptacle.

The connectors specified by the USB committee were designed to support a number of USB's underlying goals, and to reflect lessons learned from the varied menagerie of connectors then in service. Image File history File linksMetadata Download high-resolution version (1024x768, 152 KB)By Richard Wheeler (Zephyris) 2007. ... Image File history File linksMetadata Download high-resolution version (1024x768, 152 KB)By Richard Wheeler (Zephyris) 2007. ...

  • The connectors are particularly cheap to manufacture.[citation needed]

Usability

  • It is difficult to incorrectly attach a USB connector. Connectors cannot be plugged-in upside down, and it is clear from the appearance and kinesthetic sensation of making a connection when the plug and socket are correctly mated. However, it is not obvious at a glance to the inexperienced user (or to a user without sight of the installation) which way around the connector goes, so it is often necessary to try both ways.
  • Only a moderate insertion/removal force is needed (by specification). USB cables and small USB devices are held in place by the gripping force from the receptacle (without the need for the screws, clips, or thumbturns that other connectors require). The force needed to make or break a connection is modest, allowing connections to be made in awkward circumstances or by those with motor disabilities.
  • The connectors enforce the directed topology of a USB network. USB does not support cyclical networks, so the connectors from incompatible USB devices are themselves incompatible. Unlike other communications systems (e.g. RJ-45 cabling) gender-changers are almost never used, making it difficult to create a cyclic USB network.
USB extension cord

Proprioception (from Latin proprius, meaning ones own) is the sense of the position of parts of the body, relative to other neighbouring parts of the body. ... For other uses, see Topology (disambiguation). ... Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution (3072 × 2048 pixel, file size: 1. ... Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution (3072 × 2048 pixel, file size: 1. ...

Durability

  • The connectors are designed to be robust. Many previous connector designs were fragile, with pins or other delicate components prone to bending or breaking, even with the application of only very modest force. The electrical contacts in a USB connector are protected by an adjacent plastic tongue, and the entire connecting assembly is usually further protected by an enclosing metal sheath. As a result USB connectors can safely be handled, inserted, and removed, even by a small child. The encasing sheath and the tough molded plug body mean that a connector can be dropped, stepped upon, even crushed or struck, all without damage; a considerable degree of force is needed to significantly damage a USB connector.
  • The connector construction always ensures that the external sheath on the plug contacts with its counterpart in the receptacle before the four connectors within are connected. This sheath is typically connected to the system ground, allowing otherwise damaging static charges to be safely discharged by this route (rather than via delicate electronic components). This means of enclosure also means that there is a (moderate) degree of protection from electromagnetic interference afforded to the USB signal while it travels through the mated connector pair (this is the only location when the otherwise twisted data pair must travel a distance in parallel). In addition, the power and common connections are made after the system ground but before the data connections. This type of staged make-break timing allows for safe hot-swapping and has long been common practice in the design of connectors in the aerospace industry..............

The word sheath has a number of related meanings in English. ...

Compatibility

  • The USB standard specifies relatively low tolerances for compliant USB connectors, intending to minimize incompatibilities in connectors produced by different vendors (a goal that has been very successfully achieved). Unlike most other connector standards, the USB specification also defines limits to the size of a connecting device in the area around its plug. This was done to avoid circumstances where a device complies with the connector specification but its large size blocks adjacent ports. Compliant devices must either fit within the size restrictions or support a compliant extension cable which does.
  • Two-way communication is also possible. In general, cables have only plugs, and hosts and devices have only receptacles: hosts having type-A receptacles and devices type-B. Type-A plugs only mate with type-A receptacles, and type-B with type-B. However, an extension to USB called USB On-The-Go allows a single port to act as either a host or a device — chosen by which end of the cable plugs into the socket on the unit. Even after the cable is hooked up and the units are talking, the two units may "swap" ends under program control. This facility targets units such as PDAs where the USB link might connect to a PC's host port as a device in one instance, yet connect as a host itself to a keyboard and mouse device in another instance.

USB On-The-Go (normally abbreviated USB OTG) is a supplement to the USB 2. ... User with Treo (PDA with smartphone functionality) Personal digital assistants (PDAs) are handheld computers, but have become much more versatile over the years. ...

Types of USB connector

USB Connectors
USB Connectors
Different types of USB connectors from left to right• micro USB plug• mini USB plug• B-type plug• A-type receptacle• A-type plug
Different types of USB connectors from left to right
• micro USB plug
• mini USB plug
• B-type plug
• A-type receptacle
• A-type plug
Pin configuration of the USB connectors Standard A/B, viewed from face of plug
Pin configuration of the USB connectors Standard A/B, viewed from face of plug

There are several types of USB connectors, and some have been added as the specification has progressed. The original USB specification detailed Standard-A and Standard-B plugs and receptacles. The first engineering change notice to the USB 2.0 specification added Mini-B plugs and receptacles. Image File history File links Metadata Size of this preview: 800 × 372 pixelsFull resolution (1497 × 696 pixel, file size: 309 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Metadata Size of this preview: 800 × 372 pixelsFull resolution (1497 × 696 pixel, file size: 309 KB, MIME type: image/jpeg) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Usb. ... Image File history File links Usb. ...


The Mini-B, Micro-A, Micro-B , and Micro-AB connectors are used for smaller devices such as PDAs, mobile phones or digital cameras. The Standard-A plug is approximately 4 by 12 mm, the Standard-B approximately 7 by 8 mm, and the Micro-A and Micro-B plugs approximately 2 by 7 mm.


Micro-USB is a further connector, that was announced by the USB-IF on January 4, 2007.[8] It is intended to replace the Mini-USB plugs used in many new smartphones and Personal digital assistants. This Micro-USB plug is rated for 10,000 connect-disconnect cycles. It is about half the height of the mini-USB connector, but features a similar width. In the Universal Serial Bus Micro-USB Cables and Connectors Specification, details have been laid down for Micro-A plugs, Micro-AB receptacles, and Micro-B plugs and receptacles, along with a Standard-A receptacle to Micro-A plug adapter. The carrier led group OMTP have recently endorsed micro-USB as the standard connector for data and power on mobile devices.[9] The USB Implementers Forum, USB-IF, is a non-profit organisation to promote and support the Universal Serial Bus. ... is the 4th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... A Sony Ericsson Smartphone (Model P910i) with touch screen and QWERTY keyboard Look up smartphone in Wiktionary, the free dictionary. ... Look up PDA in Wiktionary, the free dictionary. ... The open mobile terminal platform (OMTP) is a standard created by the OMTP group for providing a common application framework for mobile telephones. ...


Proprietary connectors and formats

Microsoft's original Xbox game console uses standard USB 1.1 signaling in its controllers and memory cards, but features proprietary connectors and ports. Similarly, IBM UltraPort uses standard USB signaling, but via a proprietary connection format. American Power Conversion uses USB signaling and HID device class on its uninterruptible power supplies using 10P10C connectors. HTC, a company which makes Windows Mobile-based Communicators, has a proprietary connector called HTC ExtUSB, which combines mini-USB with audio input and output. Nokia includes a USB connection as part of the Pop-Port connector on their mobile phones. The second-generation iPod Shuffle uses a TRS connector to carry USB, audio, or power signals. For the Xboxs successor, see Xbox 360. ... The Nintendo GameCube is an example of a popular video game console. ... IBM UltraPort was a nonstandard USB 1. ... American Power Conversion Corp. ... An uninterruptible power supply (UPS), sometimes called an uninterruptible power source, is a device which maintains a continuous supply of electric power to connected equipment by supplying power from a separate source when utility power is not available. ... The 10P10C modular connector type is a type of electrical connector. ... HTC ExtUSB is a new proprietary USB connector used on HTC phones. ... This article is about the telecommunications corporation. ... Pop-Port connector of an original Nokia HS-5 headset The Pop-Port interface (originally coded named Tomahawk) is a plug-in port, available with many Nokia mobile phones. ... iPod shuffle is an iPod digital audio player designed and marketed by Apple Inc. ... TRS connector Triple contact plug as described in 1907. ...


USB Cables

Pin Name Cable colour Description
1 VCC Red +5V
2 D− White Data −
3 D+ Green Data +
4 GND Black Ground

The maximum length of a standard USB cable is 5.0 meters (16.4 ft). The primary reason for this limit is the maximum allowed round-trip delay of about 1500 ns. If a USB device does not answer to host commands within the allowed time, the host considers the command to be lost. When USB device response time, delays from using the maximum number of hubs and delays from cables connecting the hubs, host and device are summed, the maximum delay caused by a single cable turns out to be 26 ns [10]. The USB 2.0 specification states that the cable delay must be less than 5.2 ns per meter, which means that maximum length USB cable is 5 meters long. However, this is also very close to the maximum possible length when using a standard copper cable.

Miniplug/Microplug
Pin Name Color Description
1 VCC Red +5 V
2 D- White Data -
3 D+ Green Data +
4 ID none permits distinction of

Micro-A- and Micro-B-Plug


Type A: connected to Ground


Type B: not connected

5 GND Black Signal Ground

The data cables are a twisted pair to reduce noise and crosstalk.


Image:USB Twisted Pair.svg


Maximum Useful Signalling Distance

Although a single cable is limited to 5 meters, the USB specification permits up to five USB hubs in a long chain of cables and hubs. Consquently the maximum possible signalling distance is 30 meters, using six 5-meter cables and five hubs. In actual use, the last hub is a more convenient endpoint since some USB devices include built-in cables intended to directly connect to a hub, setting the maximum useful signalling distance at 25 meters.


Because USB is able to provide power for additional devices connected to the bus, a special type of USB extender cable was created which consists of a miniature one-port USB hub molded into one end of a 5 meter cable. These mini-hubs are fully self-contained within the cable, requiring no separate bulky hub device, and are as simple to use as plugging cables together, with each hub drawing power through all the previous single-port hubs in the chain.


The bus power is limited however, so the most practical application is to use four single-port hub extender cables, one plain 5 meter cable, and then a powered multiport hub at the very end to support multiple additional USB devices. This is especially useful where a cool and quiet work area is needed, permitting a keyboard, mouse, flash drive, printer, etc to be used 25 meters from a loud heat-generating computer.


Power

The USB specification provides a 5 V (volts) supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines.[11] Initially, a device is only allowed to draw 100 mA. It may request more current from the upstream device in units of 2 mA up to a maximum of 500 mA. Josephson junction array chip developed by NIST as a standard volt. ...


If a bus-powered hub is used, the devices downstream may only use a total of four units — 400 mA — of current. This limits compliant bus-powered hubs to 4 ports. The host operating system typically keeps track of the power requirements of the USB network and may warn the computer's operator when a given segment requires more power than is available.


On-The-Go and Battery Charging Specification both add new powering modes to the USB specification. The latter specification allows USB devices to draw up to 1.5 A from hubs and hosts that follow the Battery Charging Specification.


As of June 14, 2007, all new mobile phones applying for a license in China are required to use the USB port as a power port.[12][13] is the 165th day of the year (166th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ...


In September, 2007 the Open Mobile Terminal Platform—a forum dominated by mobile network operators but including manufacturers such as Nokia, Samsung, Motorola, Sony Ericsson and LG—announced that its members had agreed on micro-USB as the future common connector for mobile devices. [14][15] The Open Mobile Terminal Platform (OMTP) is a forum funded by companies from across the mobile phone value chain, set up with the aim of simplifying the customer experience of mobile data services. ...


Non-standard Devices

A number of USB devices require more power than is permitted by the specifications for a single port. This is a common requirement of external hard and optical disc drives and other devices with motors or lamps. Such devices can be used with an external power supply of adequate rating, which is allowed by the standard, or by means of a dual input USB cable, one input of which is used for power and data transfer, the other solely for power, which makes the device a non-standard USB device. Some external hubs may, in practice, supply more power to USB devices than required by the specification but a standard compliant device must not depend on this.


Some non-standard USB devices use the 5 V power supply without participating in a proper USB network. These are usually referred to as USB decorations. The typical example is a USB-powered reading light; fans, mug heaters, battery chargers (particularly for mobile telephones) and even miniature vacuum cleaners are available. In most cases, these items contain no digitally based circuitry, and thus are not proper USB devices at all. This can cause problems with some computers — the USB specification requires that devices connect in a low-power mode (100 mA maximum) and state how much current they need, before switching, with the host's permission, into high-power mode. A USB Christmas Tree A USB decoration is a device that uses the Universal Serial Bus (USB) protocol on a computer or other host, and is primarily a decorative device (using the USB port for power). ...


In addition to limiting the total average power used by the device, the USB specification limits the inrush current (to charge decoupling and bulk capacitors) when the device is first connected; otherwise, connecting a device could cause glitches in the host's internal power. Also, USB devices are required to automatically enter ultra low-power suspend mode when the USB host is suspended; many USB hosts do not cut off the power supply to USB devices when they are suspended since resuming from the suspended state would become a lot more complicated if they did.


There are also devices at the host end that do not support negotiation, such as battery packs that can power USB powered devices; some provide power, while others pass through the data lines to a host PC. USB Power adapters convert utility power and/or power from a car's electrical system to run attached devices. Some of these devices can supply up to 1 A of current. Without negotiation, the powered USB device is unable to inquire if it is allowed to draw 100 mA, 500 mA, or 1 A.


PoweredUSB

Main article: PoweredUSB

PoweredUSB uses standard USB signaling with the addition of extra power lines. It uses 4 additional pins to supply up to 6A at either 5V, 12V, or 24V (depending on keying) to peripheral devices. The wires and contacts on the USB portion have been upgraded to support higher current on the 5V line, as well. This is commonly used in retail systems and provides enough power to operate stationary barcode scanners, printers, pin pads, signature capture devices, etc. This standard was developed by IBM, NCR, and FCI/Berg. It is essentially two connectors stacked such that the bottom connector accepts a standard USB plug and the top connector takes a power connector. PoweredUSB, also known as Retail USB, USB PlusPower, USB +Power, is an addition to the Universal Serial Bus standard that allows for higher-power devices to obtain power through their USB host instead of requiring an independent power supply. ... PoweredUSB, also known as Retail USB, USB PlusPower, USB +Power, is an addition to the Universal Serial Bus standard that allows for higher-power devices to obtain power through their USB host instead of requiring an independent power supply. ... The BancNet (BN) Point-Of-Sale System is a local PIN-based electronic funds transfer (EFTPOS) payments solution operated by BancNet on behalf of the member banks and China UnionPay (CUP). ...


USB compared with FireWire

USB was originally seen as a complement to FireWire (IEEE 1394), which was designed as a high-speed serial bus which could efficiently interconnect peripherals such as hard disks, audio interfaces, and video equipment. USB originally operated at a far lower data rate and used much simpler hardware, and was suitable for small peripherals such as keyboards and mice. The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ...


The most significant technical differences between FireWire and USB include the following:

  • USB networks use a tiered-star topology, while FireWire networks use a repeater-based topology.
  • USB uses a "speak-when-spoken-to" protocol; peripherals cannot communicate with the host unless the host specifically requests communication. A FireWire device can communicate with any other node at any time, subject to network conditions.
  • A USB network relies on a single host at the top of the tree to control the network. In a FireWire network, any capable node can control the network.
  • USB runs with a 5v power line, whereas Firewire can supply up to 30v.

These and other differences reflect the differing design goals of the two buses: USB was designed for simplicity and low cost, while FireWire was designed for high performance, particularly in time-sensitive applications such as audio and video. Although similar in theoretical maximum transfer rate, in real-world use, especially for high-bandwidth use such as external hard-drives, FireWire 400 generally, but not always, has a significantly higher throughput than USB 2.0 Hi-Speed.[16][17][18][19] The newer FireWire 800 standard is twice as fast as FireWire 400 and outperforms USB 2.0 Hi-Speed both theoretically and practically.[20] The chipset and drivers used to implement USB and Firewire have a crucial impact on how much of bandwidth prescribed by the specification is achieved in the real world, along with compatibility with peripherals.[21] Audio peripherals in particular are affected by the USB driver implementation.[22] This article or section does not cite its references or sources. ...


One reason USB supplanted FireWire, and became far more widespread, is cost; FireWire is more expensive to implement, producing more expensive hardware.


Version history

Prereleases

Hi-Speed USB Logo
Hi-Speed USB Logo
USB OTG Logo
  • USB 0.7: Released in November 1994.
  • USB 0.8: Released in December 1994.
  • USB 0.9: Released in April 1995.
  • USB 0.99: Released in August 1995.
  • USB 1.0 Release Candidate: Released in November 1995.

Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links Otg_usb. ... Image File history File links Otg_usb. ... USB On-The-Go (normally abbreviated USB OTG) is a supplement to the USB 2. ...

USB 1.0

  • USB 1.0: Released in January 1996.
    Specified data rates of 1.5 Mbit/s (Low-Speed) and 12 Mbit/s (Full-Speed). Did not anticipate or pass-through monitors. Few such devices actually made it to market.
  • USB 1.1: Released in September 1998.
    Fixed problems identified in 1.0, mostly relating to hubs. Earliest revision to be widely adopted.

USB 2.0

  • USB 2.0: Released in April 2000.
    Added higher maximum speed of 480 Mbit/s (now called Hi-Speed). Further modifications to the USB specification have been done via Engineering Change Notices (ECN). The most important of these ECNs are included into the USB 2.0 specification package available from USB.org:
    • Mini-B Connector ECN: Released in October 2000.
      Specifications for Mini-B plug and receptacle. These should not be confused with Micro-B plug and receptacle.
    • Errata as of December 2000: Released in December 2000.
    • Pull-up/Pull-down Resistors ECN: Released in May 2002.
    • Errata as of May 2002: Released in May 2002.
    • Interface Associations ECN: Released in May 2003.
      New standard descriptor was added that allows multiple interfaces to be associated with a single device function.
    • Rounded Chamfer ECN: Released in October 2003.
      A recommended, compatible change to Mini-B plugs that results in longer lasting connectors.
    • Unicode ECN: Released in February 2005.
      This ECN specifies that strings are encoded using UTF-16LE. USB 2.0 did specify that Unicode is to be used but it did not specify the encoding.
    • Inter-Chip USB Supplement: Released in March 2006.
    • On-The-Go Supplement 1.3: Released in December 2006.
      USB On-The-Go makes it possible for two USB devices to communicate with each other without requiring a separate USB host. In practice, one of the USB devices acts as a host for the other device.
    • Battery Charging Specification 1.0: Released in March 2007.
      Adds support for dedicated chargers (power supplies with USB connectors), host chargers (USB hosts that can act as chargers) and the No Dead Battery provision which allows devices to temporarily draw 100 mA current after they have been attached. If a USB device is connected to dedicated charger or host charger, maximum current drawn by the device may be as high as 1.5 A. (Note that this document is not distributed with USB 2.0 specification package.)
    • Micro-USB Cables and Connectors Specification 1.01: Released in April 2007.
    • Link Power Management Addendum ECN: Released in July 2007.
      This adds a new power state between enabled and suspended states. Device in this state is not required to reduce its power consumption. However, switching between enabled and sleep states is much faster than switching between enabled and suspended states, which allows devices to sleep while idle.
    • High-Speed Inter-Chip USB Electrical Specification Revision 1.0: Released in September 2007.

In computing, UTF-16 (16-bit Unicode Transformation Format) is a variable-length character encoding for Unicode, capable of encoding the entire Unicode repertoire. ... The Unicode Standard, Version 5. ... USB On-The-Go (normally abbreviated USB OTG) is a supplement to the USB 2. ...

USB 3.0

  • USB 3.0 (Future version): On September 18, 2007, Pat Gelsinger demonstrated USB 3.0 at the Intel Developer Forum. USB 3.0 is targeted at ten times the current bandwidth, reaching roughly 4.8 Gbit/s by utilizing two additional high-speed differential pairs for "Superspeed" mode, and with the possibility for optical interconnect.[23][24] The USB 3.0 specification is planned to be released in the first half of 2008, commercial products are expected to arrive in 2009 or 2010.[25]
  • Backwards-Compatibility and Efficiency: USB 3.0 is designed to be backwards-compatible with USB 2.0 and USB 1.1 and employs more efficient protocols to conserve power.[26]

is the 261st day of the year (262nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Pat Gelsinger was the first Chief Technology Officer of Intel Corporation. ... Intel Developer Forum (IDF), is a twice yearly gathering of technologists to discuss Intel products and products based around Intel products. ... A gigabit per second (Gbps or Gbit/s) is a unit of data transmission equal to 1,000 megabits per second or 1,000,000 kilobits per second or 1,000,000,000 bits per second. ...

Related technologies

The PictBridge standard allows for interconnecting consumer imaging devices. It typically uses USB as the underlying communication layer. PictBridge is an industry standard from the Camera & Imaging Products Association (CIPA) for direct printing. ...


The USB Implementers Forum is working on a wireless networking standard based on the USB protocol. Wireless USB is intended as a cable-replacement technology, and will use ultra-wideband wireless technology for data rates of up to 480 Mbit/s. Wireless USB is well suited to wireless connection of PC centric devices, just as Bluetooth is now widely used for mobile phone centric personal networks (at much lower data rates). Wireless networks are telephone or computer networks that use radio as their carrier or physical layer. ... Wireless USB is a short-range, high-bandwidth wireless extension to USB that combines the speed and ease-of-use of USB 2. ... Ultra-wideband (also UWB, and ultra-wide-band, ultra-wide band, etc. ... Bluetooth logo This article is about the electronic protocol named after Harald Bluetooth Gormson. ...


See also

U3 LLC is a joint venture that is backed by Sandisk and its subsidiary, M-Systems. ... Streaming media is just-in-time delivery of multimedia information. ... Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. ... CEA-936-A (USB Carkit Specification) is a CEA standard to allow the use of a mini-USB connector for UART and analog audio signals. ... ACCESS.bus (or A.b) is a peripheral-interconnect computer bus developed by Philips in the early 1990s. ... Serial Cables are typically used for RS-232 communication. ... For other uses of SATA or Sata, see SATA (disambiguation). ... Wireless USB is a short-range, high-bandwidth wireless extension to USB that combines the speed and ease-of-use of USB 2. ... The ability to connect Ethernet devices via USB ports is known as Ethernet over USB. There are many low cost commercial adapters available to do this. ... This is a list of device bandwidths: the channel capacity (or, more informally, bandwidth) of some computer devices employing methods of data transport is listed by bit/s, kilobit/s (kbit/s), megabit/s (Mbit/s), or gigabit/s (Gbit/s) as appropriate and also MB/s or megabytes per... The HP-IL (Hewlett-Packard Interface Loop) is a short range network cable enabling several devices such as printers, floppy disk drives, tape readers, etc. ... Early ADB device Apple Desktop Bus (or ADB) is an obsolete bit-serial bus for connecting low-speed devices to computers. ... The 6-pin and 4-pin FireWire 400 Connectors The alternative ethernet-style cabling used by 1394c FireWire is Apple Inc. ... Not to be confused with PlayStation 2. ... A male DE-9 connector. ...

References

Link three should probably be http://www.ibm.com/developerworks/power/library/pa-spec7.html I looked at the link it is currently set at, and although it has to iMacs, it has little to do with USB.

  1. ^ Wireless USB — First High-Speed Personal Wireless Interconnect (PDF). USB.org (February 19, 2004). Retrieved on 2007-08-25.
  2. ^ iMac - Technical Specification
  3. ^ Standards and specs: The ins and outs of USB
  4. ^ "USB Developers Approve Micro-USB Connector Specification", InformationWeek, January 4, 2007. Retrieved on 2007-08-25. 
  5. ^ USB Class Codes at USB.org
  6. ^ USB in a NutShell - Chapter 2 - Hardware. Beyond Logic.org. Retrieved on 2007-08-25.
  7. ^ How Fast Does A USB 2.0 Drive Go On The Newest Macs? How Does It Compare To FireWire?. Bare Facts (May 8, 2004). Retrieved on 2007-08-25.
  8. ^ USB Implementers Forum (2007-01-04). "Mobile phones to adopt new, smaller USB connector" (PDF). Press release. Retrieved on 2007-01-08.
  9. ^ OMTP Local Connectivity at omtp.org
  10. ^ USB Frequently Asked Questions at USB.org
  11. ^ “7.3.2 Bus Timing/Electrical Characteristics” (ZIP). Universal Serial Bus Specification. USB.org.
  12. ^ "China to enforce universal cell phone charger", EETimes.com, May 31, 2007. Retrieved on 2007-08-25. 
  13. ^ (Chinese)The Chinese FCC's technical standard
  14. ^ "Pros seem to outdo cons in new phone charger standard", news.com, September 20, 2007. Retrieved on 2007-11-26. 
  15. ^ "Press Release: Broad Manufacturer Agreement Gives Universal Phone Cable Green Light", OTMA, September 17, 2007. Retrieved on 2007-11-26. 
  16. ^ FireWire vs. USB 2.0 - Speed Tests. Retrieved on 2007-08-25.
  17. ^ USB 2.0 vs FireWire. Digit-Life. Retrieved on 2007-08-25.
  18. ^ The Great Interface-Off: FireWire Vs. USB 2.0. PC Magazine. Retrieved on 2007-08-25.
  19. ^ Heron, Robert. USB 2.0 Versus FireWire. TechTV. Retrieved on 2007-08-25.
  20. ^ FireWire vs. USB 2.0. USB Ware. Retrieved on 2007-03-19.
  21. ^ Firewire and USB Performance. Retrieved on 2008-02-01.
  22. ^ USB 2 Audio - low latency audio. Retrieved on 2008-02-02.
  23. ^ PC World - Faster USB 3.0 Is Coming
  24. ^ Tony Smith. Revealed: USB 3.0 jacks and sockets Retrieved on 2008-01-22.
  25. ^ Shankland, Stephen. USB 3.0 brings optical connection in 2008. CNET News.com. Retrieved on 2008-01-02.
  26. ^ Mellor, Chris. Faster USB 3.0 Is Coming. PCWorld.com. Retrieved on 2008-01-02.

[[Media:Italic text]]{| style=float:right; |- | |- | |} is the 50th day of the year in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... InformationWeek is a weekly technology magazine published by CMP Media. ... is the 4th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... is the 128th day of the year (129th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 4th day of the year in the Gregorian calendar. ... For information on Wikipedia press releases, see Wikipedia:Press releases. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 8th day of the year in the Gregorian calendar. ... is the 151st day of the year (152nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... is the 263rd day of the year (264th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 330th day of the year (331st in leap years) in the Gregorian calendar. ... is the 260th day of the year (261st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 330th day of the year (331st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 237th day of the year (238th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 78th day of the year (79th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 32nd day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 33rd day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 22nd day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 2nd day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 2nd day of the year in the Gregorian calendar. ...

External links

Wikibooks
Wikibooks' Serial Programming:USB Technical Manual has more about this subject:
USB connectors

Image File history File links Wikibooks-logo-en. ...

USB 3.0

CNET Networks, Inc. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 261st day of the year (262nd in leap years) in the Gregorian calendar. ... Ars Technica is a technology-related website catering to PC enthusiasts. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 261st day of the year (262nd in leap years) in the Gregorian calendar. ... Electronic Engineering Times is a weekly magazine of the electronic industry published in the USA by CMP Media LLC. While it has a subscription cost, it is free for qualified engineers and managers of the industry. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 261st day of the year (262nd in leap years) in the Gregorian calendar. ...


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USB is arguably the most successful interconnect in computing history.
USB is now a standard feature on all PCs and makes it much easier for users everywhere to plug in everything from digital cameras to MP3 players to their PCs.
The specification for USB 2.0 was approved in April 2000.
Universal Serial Bus (USB) (607 words)
The USB connection is of course serial, and the current version (1.1) runs with a maximum throughput of 12 Mbits/second (1.5 Mbytes/second), which is shared by all devices.
USB's initial acceptance was relatively slow in coming, but once it got going, the variety of USB devices that appeared on the market surprised many people, probably including its developers.
USB remains popular for hard disks and other storage devices for those who don't have other options; however, in almost every case a higher-speed interface is a better idea if that's at all possible.
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