ec303 - chapter 6 buses interfacing

7/30/2019 EC303 - CHAPTER 6 Buses Interfacing

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EC303 COMPUTER

ARCHITECTURE

CHAPTER 6. Buses & Interfacing


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Learning Outcomes

At the end of this presentation, students will be

able to:

i. Describe a typical block diagram that shows interconnection

between components in computer.

ii. Explain the data flow between components in bus system

iii. Determine a problem involving the computers ability to

determine peripheral device.

iv. Explain the advantages of using Direct Memory Access

(DMA) to most systems


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Interconnecting System Components


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Data Flow Components in Bus

System The system bus is a cable which carries data communication

between the major components of the computer, including

the microprocessor.

The system bus consists of three different groups of wiring,

called :- the data bus,

The control bus

address bus.

These all have separate responsibilities and characteristics.


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Interconnection Between

Component in Computer


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The Control Bus

The control bus carries the signals relating to the control and

co-ordination of the various activities across the computer,

which can be sent from the control unit within the CPU

Different architectures result in differing number of lines of

wire within the control bus, as each line is used to perform aspecific task.

For instance, different, specific lines are used for each of read,

write and reset requests.


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The Data Bus

This is used for the exchange of data between the processor,

memory and peripherals, and is bi-directional so that it allows

data flow in both directions along the wires.

The number of wires used in the data bus (sometimes known

as the 'width') can differ. Each wire is used for the transfer of signals corresponding to a

single bit of binary data.

As such, a greater width allows greater amounts of data to be

transferred at the same time.


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The Address Bus

The address bus contains the connections between the

microprocessor and memory that carry the signals relating to

the addresses which the CPU is processing at that time, such

as the locations that the CPU is reading from or writing to.

The width of the address bus corresponds to the maximumaddressing capacity of the bus, or the largest address within

memory that the bus can work with.

The addresses are transferred in binary format, with each line

of the address bus carrying a single binary digit.

Therefore the maximum address capacity is equal to two to

the power of the number of lines present (2^lines).


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Introduction to Direct Memory

Access (DMA) We have seen that to move data from :

Input device to memory

Memory to output device

Memory location to memory location

Requires that the source data be moved to the processor and

then the processor data be moved to the destination


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DMA

An obvious way to improve the data transfer rate is to remove

the processor from the data transfer path. This is called DMA.

Direct memory access (DMA) is also a feature of most

computers that allows certain hardware sub modules to

access system the memory for reading and writing


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DMA

An important aspect governing the Computer System

performance is the transfer of data between memory and I/O

devices.

The operation involves loading programs or data files from disk

into memory, saving file on disk, and accessing virtual memory

pages on any secondary storage medium.


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Computer System with DMA


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Implementing DMA in a

Computer System A DMA controller implements direct memory access in a

computer system.

It connects directly to the I/O device at one end and to the

system buses at the other end. It also interacts with the CPU,

both via the system buses and two new direct connections. It is sometimes referred to as a channel. In an alternate

configuration, the DMA controller may be incorporated

directly into the I/O device.


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Data Transfer using DMA

Controller To transfer data from an I/O device to memory, the DMA

controller first sends a Bus Request to the CPU by setting BRto 1. When it is ready to grant this request, the CPU sets its

Bus grant signal, BG to 1.

The CPU also tri-states its address,data, and control lines thustruly granting control of the system buses to the DMAcontroller.

The CPU will continue to tri-state its outputs as long as BR isasserted.


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Advantages using Direct

Memory Access (DMA) Computer system performance is improved by direct transfer

of data between memory and I/O devices, bypassing the CPU.

CPU is free to perform operations that do not use system

buses.


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Input & Output Addressing

Technique


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Learning Outcomes


able to:

i. Explain two general techniques commonly used to

addressing input and output (I/O) device on the bus.

a. Isolated I/O

b. Memory mapping I/O


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INPUT-OUTPUT

ORGANIZATION Peripheral Devices

Input-Output Interface

Asynchronous Data Transfer

Modes of Transfer

Priority Interrupt

Direct Memory Access

Input-Output Processor

Serial Communication


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PERIPHERAL DEVICES

Input Devices

Keyboard

Optical input devices

- Card Reader

- Paper Tape Reader

- Bar code reader

- Digitizer

- Optical Mark Reader

Magnetic Input Devices

- Magnetic Stripe Reader

Screen Input Devices

- Touch Screen

- Light Pen

- Mouse

Analog Input Devices

Output Devices

Card Puncher, Paper Tape Puncher

CRT

Printer (Impact, Ink Jet,

Laser, Dot Matrix)

Plotter

Analog

Voice


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INPUT/OUTPUT INTERFACE Provides a method for transferring information between internal storage

(such as memory and CPU registers) and external I/O devices

Resolves the differences between the computer and peripheral devices

Peripherals - Electromechanical Devices

CPU or Memory - Electronic Device

Data Transfer Rate

Peripherals - Usually slower

CPU or Memory - Usually faster than peripherals

Some kinds of Synchronization mechanism may be needed

Unit of Information

PeripheralsByte, Block,

CPU or Memory Word

Data representations may differ


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I/O BUS AND INTERFACE

MODULES


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CONNECTION OF I/O BUS


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I/O BUS AND MEMORY BUS MEMORY BUS is for information transfers between CPU and the MM

I/O BUS is for information transfers between CPUand I/O devices through their I/O interface

Many computers use a common single bus system- for both memory and I/O interface units- Use one common bus but separate control lines for each function- Use one common bus with common control lines for both functions

Some computer systems use two separate buses,one to communicate with memory and the other with I/O interfaces

- Communication between CPU and all interface units is via a commonI/O Bus

- An interface connected to a peripheral device may have a number ofdata registers , a control register, and a status register- A command is passed to the peripheral by sending to the appropriateinterface register- Function code and sense lines are not needed (Transfer of data, control,

and status information is always via the common I/O Bus)

Functions of Buses


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ISOLATED vs MEMORY

MAPPED I/O Isolated I/O- Separate I/O read/write control lines in addition to memory read/write

control lines

- Separate (isolated) memory and I/O address spaces

- Distinct input and output instructions

Memory-mapped I/O

- A single set of read/write control lines(no distinction between memory and I/O transfer)

- Memory and I/O addresses share the common address space

> reduces memory address range available- No specific input or output instruction

> The same memory reference instructions can be used for I/O transfers

- Considerable flexibility in handling I/O operations


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Memory mapping IO

Single address space for both memory and I/O devices

disadvantage uses up valuable memory address space

I/O module registers treated as memory addresses

Same machine instructions used to access both memory and

I/O devices

advantage allows for more efficient programming

Single read line and single write lines needed

Commonly used


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Isolated IO

Separate address space for both memory and I/O devices

Separate memory and I/O select lines needed

Small number of I/O instructions

Commonly used


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Input & Output Interfacing


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Learning Outcomes


able to:

i. Define Universal Serial Bus (USB).

ii. Explain Host Controller for USB

iii. Explain items in class codes for USB


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USB

Universal Serial Bus (USB) is an industry standard developed in the

mid-1990s that defines the cables, connectors and communications

protocols used in a bus for connection, communication and power

supply between computers and electronic devices.[2]

USB was designed to standardize the connection ofcomputer

peripherals, such as keyboards, pointing devices, digital cameras,

printers, portable media players, disk drives and network adapters

to personal computers, both to communicate and to supply electric

power. It has become commonplace on other devices, such as

smartphones, PDAs and video game consoles.[3] USB has effectively

replaced a variety of earlier interfaces, such as serial and parallelports, as well as separate power chargers for portable devices.

As of 2008[update], approximately 6 billion USB ports and interfaces

are currently in the global marketplace, and about 2 billion were

being sold each year.
http://en.wikipedia.org/wiki/Industry_standardhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Bus_%28computing%29http://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Computer_peripheralhttp://en.wikipedia.org/wiki/Computer_peripheralhttp://en.wikipedia.org/wiki/Mouse_%28computing%29http://en.wikipedia.org/wiki/Portable_media_playerhttp://en.wikipedia.org/wiki/Disk_drivehttp://en.wikipedia.org/wiki/Network_interface_controllerhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Serial_porthttp://en.wikipedia.org/wiki/Parallel_porthttp://en.wikipedia.org/wiki/Parallel_porthttp://en.wikipedia.org/wiki/Power_chargerhttp://en.wikipedia.org/w/index.php?title=Universal_Serial_Bus&action=edithttp://en.wikipedia.org/w/index.php?title=Universal_Serial_Bus&action=edithttp://en.wikipedia.org/wiki/Power_chargerhttp://en.wikipedia.org/wiki/Parallel_porthttp://en.wikipedia.org/wiki/Parallel_porthttp://en.wikipedia.org/wiki/Serial_porthttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Network_interface_controllerhttp://en.wikipedia.org/wiki/Disk_drivehttp://en.wikipedia.org/wiki/Portable_media_playerhttp://en.wikipedia.org/wiki/Mouse_%28computing%29http://en.wikipedia.org/wiki/Computer_peripheralhttp://en.wikipedia.org/wiki/Computer_peripheralhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Bus_%28computing%29http://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Communications_protocolhttp://en.wikipedia.org/wiki/Industry_standard


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USB

group of seven companies began development on USB in 1994: Compaq, DEC, IBM, Intel,Microsoft, NEC and Nortel. The goal was to make it fundamentally easier to connectexternal devices to PCs by replacing the multitude of connectors at the back of PCs,addressing the usability issues of existing interfaces, and simplifying software configurationof all devices connected to USB, as well as permitting greater data rates for externaldevices.

The original USB 1.0 specification, which was introduced in January 1996, defined data

transfer rates of 1.5 Mbit/s "Low Speed" and 12 Mbit/s "Full Speed".[5]

The first widely usedversion of USB was 1.1, which was released in September 1998.

A USB Standard Type A plug, the most common USB plug

The USB 2.0 specification was released in April 2000 and was ratified by the USBImplementers Forum (USB-IF) at the end of 2001. Hewlett-Packard, Intel, LucentTechnologies (now Alcatel-Lucent), NEC and Philips jointly led the initiative to develop ahigher data transfer rate, with the resulting specification achieving 480 Mbit/s, a fortyfoldincrease over the original USB 1.1 specification.

The USB 3.0 specification was published on 12 November 2008. Its main goals were toincrease the data transfer rate (up to 5 Gbit/s), to decrease power consumption, to increasepower output, and to be backwards-compatible with USB 2.0.[7] USB 3.0 includes a new,higher speed bus called SuperSpeed in parallel with the USB 2.0 bus.[8] For this reason, thenew version is also called SuperSpeed.[9] The first USB 3.0 equipped devices were presentedin January 2010.[9][10]
http://en.wikipedia.org/wiki/Compaqhttp://en.wikipedia.org/wiki/Digital_Equipment_Corporationhttp://en.wikipedia.org/wiki/IBMhttp://en.wikipedia.org/wiki/Intelhttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/NEChttp://en.wikipedia.org/wiki/Nortelhttp://en.wikipedia.org/wiki/Mbithttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USB_Implementers_Forumhttp://en.wikipedia.org/wiki/USB_Implementers_Forumhttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/Lucent_Technologieshttp://en.wikipedia.org/wiki/Lucent_Technologieshttp://en.wikipedia.org/wiki/Philipshttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Philipshttp://en.wikipedia.org/wiki/Lucent_Technologieshttp://en.wikipedia.org/wiki/Lucent_Technologieshttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/USB_Implementers_Forumhttp://en.wikipedia.org/wiki/USB_Implementers_Forumhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Mbithttp://en.wikipedia.org/wiki/Nortelhttp://en.wikipedia.org/wiki/NEChttp://en.wikipedia.org/wiki/Microsofthttp://en.wikipedia.org/wiki/Intelhttp://en.wikipedia.org/wiki/IBMhttp://en.wikipedia.org/wiki/Digital_Equipment_Corporationhttp://en.wikipedia.org/wiki/Compaq


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usb

Prereleases

The USB standard evolved through several versions before its

official release in 1995:

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.


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Usb 1.0

USB 1.0

USB 1.0: Released in January 1996.

Specified data rates of1.5 Mbit/s (Low-Bandwidth) and

12 Mbit/s (Full-Bandwidth). Does not allow for extension

cables or pass-through monitors (due to timing and powerlimitations). Few such devices actually made it to market.

USB 1.1: Released in August 1998.

Fixed problems identified in 1.0, mostly relating to hubs.

Earliest revision to be widely adopted.


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USB 2.0

USB 2.0: Released in April 2000. Added higher maximum

bandwidth of480 Mbit/s (60 MB/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 packageavailable from USB.

A PCI USB 2.0 card for a

computer motherboard


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USB 3.0

USB 3.0 was released in November 2008. The standard

specifies a maximum transmission speed of up to 5 Gbit/s

(625 MB/s), which is more than 10 times as fast as USB 2.0

(480 Mbit/s, or 60 MB/s), although this speed is typically only

achieved using powerful professional grade or developmentalequipment. USB 3.0 reduces the time required for data

transmission, reduces power consumption, and is backward

compatible with USB 2.0.


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USB 3.0

The USB 3.0 Promoter Group announced on 17 November 2008 that

the specification of version 3.0 had been completed and had made

the transition to the USB Implementers Forum (USB-IF), the

managing body of USB specifications.[13] This move effectively

opened the specification to hardware developers for

implementation in future products. A new feature is the"SuperSpeed" bus, which provides a fourth transfer mode at 5.0

Gbit/s. The raw throughput is 4 Gbit/s (using 8b/10b encoding), and

the specification considers it reasonable to achieve around 3.2

Gbit/s (0.4 GB/s or 400 MB/s), increasing as hardware advances in

the future take hold. Two-way communication is also possible. InUSB 3.0, full-duplex communications are done when using

SuperSpeed (USB 3.0) transfer. In previous USB versions (i.e., 1.x or

2.0), all communication is half-duplex and directionally controlled by

the host.
http://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/8b/10b_encodinghttp://en.wikipedia.org/wiki/SuperSpeedhttp://en.wikipedia.org/wiki/SuperSpeedhttp://en.wikipedia.org/wiki/8b/10b_encodinghttp://en.wikipedia.org/wiki/USB


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Summary :USB

Definition:

A USB port is a standard cable connection interface on

personal computers and consumer electronics.

USB ports allow stand-alone electronic devices to be

connected via cables to a computer (or to each other). USB stands for Universal Serial Bus, an industry standard for

short-distance digital data communications.

USB allows data to be transferred between devices. USB ports

can also supply electric power across the cable to deviceswithout their own power source


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Host Controller Interface

A host controller interface (HCI) is a register-level interface

that enables a host controller for USB or FireWire hardware to

communicate with a host controller driver in software. The

driver software is typically provided with an operating system

of a personal computer, but may also be implemented byapplication-specific devices such as a microcontroller.

On the expansion card or motherboard controller, this involves

much custom logic, with digital logic engines in FPGAs plus

analog circuitry managing the high-speed differential signals.

On the software side, it requires a device driver (called a HostController Driver, or HCD).
http://en.wikipedia.org/wiki/Interface_%28computer_science%29http://en.wikipedia.org/wiki/Host_controllerhttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/FireWirehttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Microcontrollerhttp://en.wikipedia.org/wiki/Expansion_cardhttp://en.wikipedia.org/wiki/Field-programmable_gate_arrayhttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Device_driverhttp://en.wikipedia.org/wiki/Device_driverhttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Field-programmable_gate_arrayhttp://en.wikipedia.org/wiki/Expansion_cardhttp://en.wikipedia.org/wiki/Microcontrollerhttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Operating_systemhttp://en.wikipedia.org/wiki/FireWirehttp://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/Host_controllerhttp://en.wikipedia.org/wiki/Interface_%28computer_science%29


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USB HOST CONTROLLER

A Universal Serial Bus (USB) host controller is an interface thatallows an enabled piece of hardware to interact and communicatewith a particular piece of software. The USB connection is an inputand output port that comes standard with most computers and avariety of other digital equipment that allows data to be transmittedthrough a cable or any other form of direct connection. A USB host

controller manages the communication between peripheral devicesand the computer system. Most modern computers have hi-speedUSB host controllers and many older computers can have a hostcontroller easily installed in an open slot on its motherboard.

A hi-speed USB host controller maintains a connection betweensuch devices as a keyboard, mouse, modem or printer and ensuresthat the computer's operating system recognizes the device. Theoperating system relies on the USB host controller in order to avoidhaving to install individual drivers for every device connected. EveryUSB device communicates with the computers operating system ina standard programming language, such as C++.
http://www.wisegeek.com/what-is-a-motherboard.htmhttp://www.wisegeek.com/what-is-a-motherboard.htmhttp://www.wisegeek.com/what-is-a-modem.htmhttp://www.wisegeek.com/what-is-a-modem.htmhttp://www.wisegeek.com/what-is-a-modem.htmhttp://www.wisegeek.com/what-is-a-motherboard.htm


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Host Controller for USB

i. Open Host Controller Interface

ii. Universal Host Controller Interface (UHCI)

iii. Enhanced Host Controller Interface (EHCI)

iv. eXtensible Host Controller Interface (xHCI)


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Open Host Controller Interface

The OHCI standard for USB is similar, but supports USB 1.1 (full

and low speeds) only; so as a result its register interface looks

completely different. Compared with UHCI, it moves more

intelligence into the controller, and thus is accordingly muchmore efficient; this was part of the motivation for defining it.

If a computer provides non-x86 USB 1.1, or x86 USB 1.1

without an Intel or VIA chipset, it probably uses OHCI (e.g.

OHCI is common on add-in PCI Cards based on an NEC

chipset).
http://en.wikipedia.org/wiki/USBhttp://en.wikipedia.org/wiki/USB


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Universal Host Controller Interface (UHCI) was created by

Intel for USB 1.0 (full and low speeds).

Far from being "universal", it is actually proprietary and is

incompatible with OHCI. Intel and VIA controllers generally

use UHCI, while other vendors use OHCI.
http://en.wikipedia.org/wiki/Universal_Serial_Bushttp://en.wikipedia.org/wiki/Proprietary_hardwarehttp://en.wikipedia.org/wiki/Proprietary_hardwarehttp://en.wikipedia.org/wiki/Universal_Serial_Bus


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Enhanced Host Controller Interface (EHCI) is a high-speed controllerstandard that is publicly specified. The USB-IF insisted on this forUSB 2.0 instead of having a different standard for PCI-based USBinterfaces, which would have increased complexity and thereforecosts. Intel hosted the EHCI conformance testing, which helped toprevent divergence from the standard.

EHCI only provides high-speed USB functions. It relies on a"companion controller", either OHCI or UHCI, to handle full- andlow-speed devices. Motherboards and PCI Cards that provide high-speed ports thus have two controllers, one handling high-speeddevices and the other handling low- and full-speed devices.

It is not uncommon to find UHCI, OHCI and EHCI all co-existing in a

standard PC, with a UHCI driver providing low- and full-speedfunctions on the (Intel chipset) motherboard, an OHCI driverproviding low- and full-speed functions for the USB ports on an add-in (NEC chipset) PCI expansion card, and an EHCI driver providinghigh-speed functions for the USB ports on that expansion card.
http://en.wikipedia.org/wiki/USB-IFhttp://en.wikipedia.org/wiki/USB-IFhttp://en.wikipedia.org/wiki/USB-IFhttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/Conformance_testinghttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/Conformance_testinghttp://en.wikipedia.org/wiki/Conformance_testinghttp://en.wikipedia.org/wiki/Costhttp://en.wikipedia.org/wiki/USB-IFhttp://en.wikipedia.org/wiki/USB-IFhttp://en.wikipedia.org/wiki/USB-IF


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eXtensible Host Controller Interface (xHCI) is the newest host

controller standard that improves speed, power efficiency and

virtualization over its predecessors The goal was also to define

a USB host controller to replace UHCI/OHCI/EHCI. It supports

all USB device speeds (USB 3.0 SuperSpeed, USB 2.0 Low-,Full-, and High-speed, USB 1.1 Low- and Full-speed).

ec303 - chapter 6 buses interfacing

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