Milestone-Proposal:Universal Serial Bus (USB)
|more than 25 years=Yes
|within fields of interest=Yes
|benefit to humanity=Yes
|ou is paying=Yes
|ou is arranging dedication=Yes
|section is taking responsibility for plaque=Yes
|a1=Universal Serial Bus (USB), 1996
|plaque citation=An industry consortium published the first Universal Serial Bus (USB) specification in January 1996. Intended to simplify attaching electronic devices to a computer, and initially directed to PCs, USB became a very successful industry-wide interface. Its versatile architecture supported new classes of devices, power delivery, battery charging, and high speed, while remaining low cost for home and business use. USB's cabling, connectors, and logo became recognizable worldwide.
|IEEE units paying=
Unit: Oregon Section
Senior Officer Name: Paulo Vasconcelos
|IEEE units arranging=
Senior Officer Name: Paulo Vasconcelos
|IEEE sections monitoring=
IEEE Section: Oregon
IEEE Section Chair name: Paulo Vasconcelos
Proposer name: Brian A. Berg
Proposer email: Proposer's email masked to public
|a2a=Intel Corporation, 2111 NE 25th Ave, Hillsboro, OR 97124 (Intel Jones Farm Campus) 45.543941 122.962248 |a7=In the lobby of the Jones Farm Conference Center (JFCC) on the Intel Jones Farm Campus |a8=Yes |mounting details=On a wall in the lobby of the JFCC |a9=There is a security guard, and the lobby is open to the public during normal business hours |a10=Intel Corporation |a4=The key initial importance of USB was its impact on transforming the task of attaching and removing devices from computers from a process that required technical skills and patience into one that was as easy as inserting or removing a cable – a process dubbed as “Plug and Play.” USB thereby made computers more user friendly, whether it be at home, in an office setting, or in a data center. USB’s popularity led to other uses such charging batteries in cell phones and becoming the power connector for computers. As a result, USB has become ubiquitous on most computerized devices, and its logo and cabling are recognized worldwide.
•Expanding the capabilities PC-class computers was difficult before the mid-1990s
Until the mid-1990s, it was difficult for anyone without some technical skills to significantly expand the capabilities of IBM PC-class computers. For the general consumer world, such a task was practical only for “hobbyists.” For the business world, an IT department whose staff could configure and support system reconfigurations or expansions was generally required.
The means by which new hardware could be added to PCs was usually by using one or more of the following: the serial port, the parallel port (which sometimes adhered to the IEEE 488 standard), and an expansion board that was installed in an open slot in the computer’s internal motherboard. For example, adding a new device such as a digital scanner typically required opening up the PC and installing an expansion board that used either SCSI or some proprietary protocol. Such a task could include unscrewing and uncabling some existing components, manipulating jumpers and/or dip switches to configure DMA channels and IRQ request lines, and often much trial and error while having to power the PC on and off each time a change was made before the scanner could operate.
Many of the problems encountered were due to the lack of standard practices amongst the many suppliers in the industry, and thus the difficulty of describing the necessary steps for adding the new hardware because of, for example, the configuration of devices already installed on the PC. As such, adding new hardware and returning the PC to a fully working condition was often a difficult task even for skilled hobbyists and professionals. The non-technical consumer public would either rely on staff at a computer store to undertake such a task, or they would not even consider adding a new device such as a scanner Retail computer superstore CompUSA reported that their product return rate for scanners was over 30%, and that the impact of these returns resulted in a net loss for the entirety of their scanner sales at that time.
•The Plug and Play Standard
An effort called “Plug and Play” (abbreviated as PnP) began in the 1990s as part of an industry-wide effort to allow a PC to automatically self-configure both its hardware and software in order to accommodate the addition of a new device with little or no effort by the user. PnP was intended to be automatically invoked when new hardware was installed inside the PC, but also to accommodate “hot swapping” a device so as to not require the PC to first be powered off. Thus, the computer would automatically recognize any new device, load new software drivers if needed, and allow the newly-connected device to be usable.
PnP was a collection of methods for determining and controlling system resource usage, and thereby required that a PC’s motherboard, system BIOS and peripherals all be PnP-compliant. A number of hardware and software companies developed the PnP standard for the control of all system resources so that changes could be dynamically performed when the computer was booted after a reconfiguration, as well as by plugging or unplugging a device while the computer was running.
ISA PnP in 1993 defined hardware methods for detecting and configuring expansion cards, but typically didn’t expect those card to be re-configured during normal operation. A document titled [[Media:PnP-BIOS-Specification-V1.0A.pdf]Plug and Play BIOS Specification Version 1.0A] was published on May 5, 1994 jointly by Compaq Computer Corp., Phoenix Technologies, Ltd. and Intel Corp. to define requirements for the system BIOS aspect of PnP, and soon thereafter Intel started shipping motherboards equipped with a PnP BIOS.
Released in August 1995, Microsoft’s Windows 95 operating system’s major architectural changes as compared with its Windows 3.1 predecessor were critical to advancing PnP in the industry. Its System Registry worked with a comprehensive scheme of enumerating hardware at boot time, and the ability to dynamically allocate and deallocate resources as hardware was added or removed from a running PC. An essential Windows 95 PnP component was its "Add New Hardware" wizard which recognized when new hardware was attached, and which would guide the user through any steps necessary to allow its use.
•Intel initiated the efforts that led to USB’s creation
Intel recognized that PnP needed a whole new interface protocol that would replace the PC’s parallel and serial interfaces with one that supported hot swapping. After initial work on a spec (initially called the “Serial Bus”) had been completed in early 1994, Jim Pappas (who had been working at Digital Equipment Corp., aka DEC) joined Intel and led the effort for this new bus. Intel invited key industry players to join a working group to further develop the spec, and their first meeting was held in May 1994 at Intel’s Jones Farm Campus in Hillsboro, OR.
The attendees brainstormed about which direction to take and which technical skills to recruit for the effort. This meeting was the birth of what was eventually called the Universal Serial Bus, or USB. This effort resulted in seven companies working together to create USB Specification Revision 1.0 as released on Jan. 15, 1996: Compaq, Digital Equipment Corp. (DEC), the IBM PC Co., Intel, Microsoft, NEC and Northern Telecom (Nortel). USB embraced PnP's self identification and configuration technologies, and required that all USB devices had to be configured before they could be used.
The introductory chapter of this first USB Specification states that the “motivation for the Universal Serial Bus comes from three interrelated considerations” which it describes as “Connection of the PC to the telephone” (due to “the merge of computing and communication” being “the basis for the next generation of productivity applications”), “Ease of use” (the difficulties resultant from the multiplicity of different means by which a device can be attached to a computer, including the serial/parallel ports discussed above, keyboard/mouse/joystick interfaces, and new interfaces created to accommodate new device types), and “Port expansion” (the limited number of ports in computers). Thus, the “lack of a bi-directional, low-cost, low-to-mid speed peripheral bus has held back the creative proliferation of peripherals.”
•The Importance of Intel’s Jones Farm Campus
While the first USB specification was being created, most interactions with outside vendors took place during regularly-scheduled conference calls. Outside vendors such as Microsoft often came to meetings at Jones Farm, and face-to-face meetings were generally hosted by various companies elsewhere. However, the Jones Farm Campus became the "epicenter" of this endeavor as hardware and software was being developed and tested collaboratively.
There is a glass conference room at the entrance of the Jones Farm 3 building (JF3) that was unique since it was accessible prior to reaching the security desk, and it had been a private conference room reserved for the most senior Intel executives. This room was allowed to be converted into a lab for a 3-month period, but it ended up being used for over 3 years by nearly every company working in the ever-growing USB industry. Dubbed the USB Product Integration Lab (PIL), it could be occupied by various companies 24 hours a day, even after the lobby was closed. As there were no USB devices, hubs or hosts in the early days, Intel created debug versions of these devices along with software drivers and test tools. All of the original furniture in the PIL was replaced with several lab benches, and every bench was filled with these debugging tools along with test equipment. Companies developing new USB products were able to use the PIL as a test and debug environment while working with Intel USB engineers in order to get USB signaling, packets and transactions operational. The companies using the PIL were often very secretive about the products that they had under development. Until at least 1996, most industry players involved in early development efforts used the PIL to debug their USB products before they went into production. Key to this effort was the availability of the first USB ICs from Intel in 1995.
•USB played an essential role in transitioning the PC into a consumer-level device
The USB standard was created by the industry to allow the PC to expand beyond just business applications by enabling a consumer-friendly way to add devices to a computer, and also enabling new usage areas such as digital music and digital photography. Essential to USB was a standard connector on the exterior of the computer which allowed any type of USB device to be dynamically plugged into or unplugged from a running computer. Most computers included at least two such connectors, and a USB hub allowed multiple devices to be supported from a single USB connector.
The fact that PnP was an essential aspect of the new Windows 95 architecture allowed the addition of support for USB by way of OEM Service Release (OSR) 2.1, which became available on August 27, 1997. Nearly every industry player, including Microsoft itself, used the USB PIL to debug and validate their products since Windows 95 was the first operating system to support the new USB standard.
USB reached a critical turning point with the June 1998 release of Windows 98 because of its support of a draft version of the USB 1.1 spec. With Windows being the world’s most popular operating system, the number of USB devices on the market began to grow dramatically. In addtion, Apple's iMac (announced in May 1998 and released in August 1998) replaced its normal mouse and keyboard connectors with a pair of USB connectors.
USB’s most significant technical challenge was containing costs. The USB design target included the mouse, the single most common pointing device at the time. Microsoft disclosed that the entire electronics budget for their optical mouse was only 50 cents. Using the mouse as the baseline, this design target set up a series of challenges regarding how to keep the design simple and inexpensive, while still allowing it to expand into areas such as imaging, storage, and synchronous applications such as music and digital telephony.
A second significant technical obstacle arose due to the desire to minimize cost. The challenge was how to accomplish all the desired communication and control functionalities using only a single differential signaling pair - essentially one logical wire. In comparison, other popular cabled connections of the time used many wires, with wires dedicated to special signals such as interrupts.
•Broad Acceptance Obstacle
USB faced a critical obstacle for its acceptance and success in the marketplace. The industry recognized the need for a simplified low-cost interface that used a single connector to support a variety of hot-swappable devices, and USB’s main competition in achieving this was IEEE 1394/FireWire and ACCESS.bus:
• IEEE 1394/FireWire:
o Like USB, it included both power and data on its cabling, but 1394 provided more power
o Like USB, it supported hot-swapping (and hence could potentially be plug-and-play)
o USB had significantly lower cost than 1394 because of its simplicity (use of a host master) as compared with 1394’s symmetric and more complex peer-to-peer architecture, as well as because its initial design was as a lower-performance interface than 1394
o While Steve Jobs was receiving a royalty from PC OEMs of $1 for each 1394 port, Intel was adding USB to its own processor chipset. Since the resultant PC OEM cost of adding USB was thus little more than the cost of adding a pair of USB connectors, the incentive to include 1394 ports in PCs was greatly diminished.
o As a result, USB connectors were included on most new PCs near the time of USB’s 1996 introduction, and USB was supported in Microsoft Windows in 1997
o USB thus marginalized 1394 to a higher-priced echelon of the consumer electronics market
• Apple Desktop Bus (ADB):
o Proprietary to Apple, and so never a direct USB competitor
o Only ever used for low-speed devices such as keyboards and mice
o Did not support hot swapping
o Introduced on the Apple IIGS in 1986, and used on Apple products until the early 2000s
o Used on some NeXT computers, and some third-party computers
o Apple replaced ADB with USB starting with the 1998 iMac (which also included FireWire)
• ACCESS.bus (A.b)
o Created by Philips and DEC for the PC as a way to reproduce much of what ADB offered
o Supported hot swapping, but its 10 kbit/sec and 100 kbit/sec speeds were much slower than USB’s slowest speeds of 1.5 Mbits/sec and 12 Mbits/sec
o ACCESS.bus Industry Group (ABIG) was formed in 1993, and included Microsoft and DEC
o Interest waned with Intel’s backing of USB, leaving Philips as the prime supporter
o ACCESS.bus thus never achieved widespread use
A “political” obstacle occurred once it was obvious that USB had broad industry support. A wide variety of requests started to arrive from adjacent markets that wanted to utilize the ubiquity and low cost expected from USB, including numerous requests for additional features which would have expanded the design of USB well beyond its original simple objectives. Examples include (1) fully symmetric and autonomous operation so that devices could communicate even if the PC was powered off, (2) long range cable lengths of up to 1 km, and (3) waterproof connectors for underwater dive computers. |a5=•USB’s Asymmetric Design Allowed for Simplicity and Lower Cost
USB was based on a strategic design choice of being asymmetric to take advantage of the fact that the host side interface would have the extensive resources available to a full PC, thus allowing design choices for the device side of the wire to be relatively simple. This decision was hugely beneficial as it (1) allowed the capabilities of a USB device to range from ultra-simplistic to highly sophisticated, (2) differentiated USB from the symmetric design and resultant higher cost of IEEE 1394/FireWire, and (3) led to a broad range of types of USB devices being possible, and which was ever-expanding.
•USB’s Inclusion of Power in Its Cabling
The early decision to supply power to attached devices was quite controversial as no widely-used computer interface provided power at that time. The main reason for this was to accommodate devices such as keyboards and mice, which could not have a separate power supply connection. Other devices were also envisioned that could be fully powered from the bus.
A big surprise was when Logitech completely re-engineered its prototype portable sheet scanner (including the use of new motors) to operate within USB’s 2.5 Watt limit. The inclusion of power often precluded the need for a wall plug power adapter (often called a “wall wart”), and this also had a huge positive impact since it allowed a single cable to attach a wide variety of devices to a PC.
•USB’s Inclusion of Power Allowed it to Eventually Function as a Charger
USB’s inclusion of power proved to be hugely beneficial to USB’s success in ways that were far beyond what anyone had envisioned in the mid-1990s. Starting in around 2006, a number of cell phone suppliers (most notably Motorola and Nokia) developed an ancillary specification for the Micro-USB connector specification that would better serve the mobile phone market. In around 2007, Qualcomm and Nokia led an effort to develop the Battery Charging Specification to enable increasing the 5-volt supply current beyond 500 mA when used for mobile phone charging. Thus, USB ports could offer up to 1.5A (7.5 Watts) when enabled for charging using a standardized discovery technique based on the termination of the USB 2.0 data bus pins, and this scheme served the mobile phone industry for several years.
Starting in 2012, competitive pressures in the explosively expanding cell phone market led to interoperability issues with the standard USB Micro-B connector as proprietary charging techniques that pushed the power boundaries beyond the USB standard's 5V @ 1.5A limitation came into use. One example is Qualcomm’s Quick Charge (QC) technology.
With the formal introduction of the USB Type-C connector in 2014, and based on the methodologies of the 2012 USB Power Delivery standard, a fully standardized USB charging solution tailored to a broad range of applications became available, and these standards have matured with the marketplace. The USB 3.1 standard allowed USB to deliver up to 100 Watts of power, and USB 3.2 standard included the previously standardized Type-C connector.
•USB’s Simple Design Was Essential to Its Success
The USB standard purposefully defined several standard device classes including mass storage, audio, video and communication. These device classes allowed OS vendors to provide standardized device drivers, and avoided having every device vendor provide their own driver. This further reduced errors in the field due to incorrectly implemented device drivers, and these have proved adequate to support a broad range of device types. It was felt that if USB was allowed to increase in complexity, a lack of focus would prevent it from remaining low-cost and achieving widespread usage. As such, the standard was created with the intent that the feature set and cost were in line with the ability of computer manufacturers to provide USB in every platform, and as part of every base configuration – and this intent has been proven in the marketplace.
This simple design allowed USB to address its targeted applications (which initially were peripherals attached to PC-class computers), and also allowed the vast majority of other device types to find a way to make USB work. Indeed, the different usages of USB have been ever-increasing over the years. Thus, while initially created to ease the difficulties of connecting new hardware to PC-class computers, USB’s simple design philosophy has led to its adoption throughout the computer, consumer electronics and mobile communications industries, into automobiles and industrial automation applications, and for power applications such as recharging batteries as well as providing primary power to computers and many other kinds of devices.
There is no other computerized interface in the world that has had anything approaching USB’s widespread acceptance – it is truly ubiquitous, and it has seen a continual increase in usage in an ever-broadening range of product categories since its 1996 introduction. In 2006 alone, over 2 billion USB devices were shipped.
•USB Implementers Forum (USB-IF)
Much of USB’s success is due to its having been designed by a broad industry coalition. As key players in that coalition were writing the USB 1.0 Specification, they created the USB Implementers Forum (USB-IF) in 1995 as a nonprofit organization, and whose main activities have been the promotion and marketing of USB, the creation and maintenance of USB ancillary standard specifications, and running a compliance program to ensure adherence to these specifications. Devices proven to comply with the USB-IF certified testing protocol can be sold with a USB-certified logo.
In addition, the USB “trident” logo was created at the time of the USB 1.0 Specification. The inclusion of this logo on cabling and adjacent to connectors has led to it becoming USB’s most universally recognized symbol. The different shapes at the tips of the trident’s three prongs represent the multiple device types able to be supported by USB, and on a single port.
• May 1994: Intel invited representatives from major industry players to a meeting at the Intel Jones Farm campus to discuss “Serial Bus,” a new serial protocol that Intel proposed to replace the antiquated serial and parallel interfaces that were then standard on PC class computers. This bus was eventually given the name Universal Serial Bus, or USB.
• Sept. 1995: USB was introduced to an industry gathering of about 700 at the Fairmont Hotel in San Jose, CA. When Jim Pappas was introduced, he walked from the back of the room to the stage while dragging behind him a large swath of cables with mice, keyboards and other peripherals attached. He started his keynote address by saying that “all of this can be replaced by just one of these” while holding up a single USB Type A connector. By the time of this event, 160 companies had registered for USB Vendor IDs.
• Jan. 15, 1996: Revision 1.0 of the USB Specification as created by seven key industry players (Compaq, Digital Equipment Corporation (DEC), the IBM PC Co., Intel, Microsoft, NEC and Northern Telecom (Nortel)) was made public. It supported speeds of 1.5 Mbits/sec and 12 Mbits/sec.
• August 27, 1997: Windows 95 OEM Service Release (OSR) 2.1 was released with support for USB, and over 1100 companies had registered for USB Vendor IDs around this timeframe.
• June 25, 1998: Windows 98 was released with support for a draft version of the USB 1.1 spec.
• August 15, 1998: the Apple iMac G3 was released without an integrated floppy drive, but with USB 1.1 support for a pair of USB connectors able to support devices including a keyboard and mouse, and with industry support for a floppy drive.
• Sept. 23, 1998: Revision 1.1 of the USB Specification was released with various embellishments and clarifications.
• April 27, 2000: Revision 2.0 of the USB Specification was released, which added high-speed mode @ 480 Mbits/sec (a 40x improvement).
• Nov. 12, 2008: Revision 3.0 of the USB Specification was released, which added SuperSpeed mode @ 5 Gbits/sec (an over 10x improvement).
• July 26, 2013: Revision 3.1 of the USB Specification was released, which added SuperSpeedPlus @ 10 Gbits/sec (a 2x improvement), and support for up to 100 Watts of power.
• Sept. 22, 2017: Revision USB 3.2 of the USB Specification was released, which added a 2nd data lane for a 2x improvement, and the Type C connector.
• August 29, 2019: the USB4 Specification was released, which expanded data transfer modes, including tunneling.
- USB 1.0: https://fl.hw.cz/docs/usb/usb10doc.pdf
- USB 1.1: http://esd.cs.ucr.edu/webres/usb11.pdf / http://www.13thmonkey.org/documentation/USB/usb11.pdf
- USB 2.0: https://www.usb.org/document-library/usb-20-specification