USB Universal Serial, is English BUS (Universal Serial Bus) abbreviation, and the Chinese referred to as "through the string line, is an external bus standard,specification for computer and external equipment connection and communication. Is the interface technology application in the field of PC. USB interface support equipment plug and play function. USB is at the end of 1994 by Intel, Compaq, IBM, Microsoft and so many companies proposed.

Brief introduction

But until recently, it has been widely applied. Since November 11, 1994: USBV0.7 version, USB version has gone through years of development, now has developed into 3 version, become the current standard in the extended interface of computer. At present, the motherboard is mainly used USB1.1 and USB2.0, the USB version can be compatible well. A 4 pin USB (USB3.0standard 9 pin plug plug) as the standard, the daisy chain form can connect all of the peripherals, can connect up to 127 peripheral equipment, and no loss ofbandwidth. USB needs three aspects of host hardware, operating system and peripheral support to work. At present, the general board were controlled bychipset supports USB function, the motherboard is provided with a USB interface socket, and besides the backboard socket on the motherboard, USB pin is left, the front of the chassis through the connection can be received asthe front USB interface to facilitate the use of (attention, should carefully read the motherboard manual and map connection, at the connection must not take the wrong and the damage of equipment). And the USB interface can alsothrough special USB link to achieve double interconnection, and can extend more interface by Hub. USB has high transmission speed (USB1.1 is 12Mbps,USB2.0 is 480Mbps, USB3.0 is 5 Gbps), easy to use, support hot swappable,flexible connection, independent power supply etc, can be connected with the mouse, keyboard, printer, scanner, camera, flash disk, MP3 machine, mobile phone, digital camera, mobile hard drives, external floppy drive light USB card,ADSL, Modem, Cable Modem, almost all the external devices. USB interface can be used to connect up to 127 peripheral such as keyboard, mouse,modem and etc.. USB since it launched in 1996, has successfully replacedserial port and parallel port, and become today's personal computer and intelligent devices must be equipped with one of the interfaces. The version ofUSB version of the maximum transmission rate difference between the title ofthe maximum output current protocol launch time USB1.01.5Mbps (192KB/s)and low speed (Low-Speed) January 500mA1996 USB1.112Mbps (1.5MB/s) at full speed (Full-Speed) September 500mA1998 USB2.0480Mbps (60MB/s)high speed (High-Speed) April 500mA2000 USB3.05Gbps (640MB/s) (Super-Speed) 900mA2008 in November for speeding

The application of USB

With the rapid development of computer hardware, peripheral equipmentincreasing, keyboard, mouse, modem, printer, scanner is already It is evident to anyone, digital camera, MP3 player come one after another, so much of theequipment, how to access the personal computer? USB is based on the objective of generating. USB is a computer peripheral equipment connectedstandardization, a single interface, the standard is composed of Intel (Intel),NEC, Compaq, DEC, IBM (Business Machines Corp), Microsoft (Microsoft),Northern Telecom contact work. USB1.1 standard interface transmission rate of 12Mbps, but a USB device only up can get the transmission bandwidth of 6Mbps. So if the external CD-ROM, at most, can receive six speed CD-ROM,no longer high. If the real-time playback MPEG-1 VCD movie, at least to thetransmission bandwidth of 1.5Mbps, this USB can do, but to finish a large amount of data of four times MPEG-2 DVD video playback, USB may be very difficult, if plus the AC-3 audio data, USB equipment is very difficult to realizethe real-time playback. A USB interface theory can support 127 device, but is still unable to achieve this figure. In fact, for a computer, which is connected to the peripheral rarely have more than 10, so the number is enough for us to use. USB also has a significant advantage is the support hot swappable, that is to say in the boot, you can safely connecting or disconnecting the USBequipment, to achieve true plug and play. However, not all Windows systems support USB. At present, there are many different versions of the Windows system, in these versions, the system only Windows98 above the support for USB is better, while the other version of Windows cannot fully support USB.For example, Windows95's retail version is not supported by USB, and onlylater bundle PC version of Windows95 to support USB. At present, USB devices have been widely used, is more common USB2.0 interface, the transmission speed of 480Mbps per second. The needs of users, is the impetus to the development of science and technology, manufacturers arealso aware of this bottleneck. At this time, COMPAQ, Hewlett Packard, Intel,Lucent, Microsoft, NEC and PHILIPS of those 7 companies jointly developed the USB 2 interface standard. USB 2 will be the speed of data transmissionbetween devices has increased to 480Mbps, than the standard USB 1.1 is about 40 times faster, the speed increase the maximum benefits for the usersmeans that users can use to external equipment more efficient, but also has many speed peripheral devices can be connected to the USB 2 on the line,and the bottleneck effect occurred without worrying about data transmission.So, if you are using USB 2 scanner, it was completely different, sweep a picture of 4M in just 0.1 seconds of time, a blink of an eye, the efficiency is greatly improved. Moreover, USB2.0 can use the same specifications as the original cable USB definition, joint regulation