The difference between USB 2.0 full speed and fast speed

It is a long time not updated, this article together number first. Say now is popular USB 3.0, but USB 2.0 of the product is still very much, HYPO occasionally see an article (original), just know that USB 2.0 also has full speed and high velocity of the distinction, if you buy a full-speed USB 2.0 mass storage device, copy a few grams of film, you will wait. There is also a noticeable difference between USB 2.0 full speed and high speeds.

In addition to the 1.5Mbps and 12Mbps two transmission modes specified in the USB1.1, the USB2.0 also adds a 480Mbps high-speed data transfer mode (note: The transmission rate of the second version of the USB2.0 will reach 800Mbps, the highest ideal value 1600Mbps). Although the transmission speed of the USB2.0 is greatly improved, its working principle and mode is exactly the same as that of USB1.1, and it is increased to 480. The most critical technique for the transmission speed of Mbps is to increase the unit transfer rate: the USB1.1 unit data transfer time is 1 milliseconds, while the USB2.0 unit data transfer time reaches 125 microseconds.

The maximum transfer rate for the USB2.0 is 480Mbps, which is 60mb/s. However, it is important to note that this is a theoretical transfer value, if a few devices share a USB channel, the main control chip will be the bandwidth allocated to each device, control. As in USB1.1, all devices can only share 1.5mb/s bandwidth. If a single device consumes all the bandwidth of the USB interface, it can be difficult for other devices to use.

USB2.0: The theoretical speed is 480Mbps, corresponding to the previous USB2.0;

USB2.0 Full speed: The theoretical velocity is 12Mbps, that is, the past USB1.1;

To choose a USB wireless card, you should know the following points:

①usb2.0 is called high-speed USB, which can achieve higher transmission speed 480mbps;usb1.1 the highest transfer rate of 12Mbps, labeled "Full-Speed USB", when purchasing USB wireless card do not "full speed" mixed to "high speed", the specific reason can see below.

The USB2.0 's wireless card has a "USB hi-speed" color map, while the USB1.1 color tag is "USB Basic speed". In addition, many manufacturers often labeled "USB2.0 ready" on the product box, or "The Faster Than USB 1.1 (40 times times faster than USB1.1)", to be aware of the distinction.

But in June 2003, the USB association renamed the USB Specifications and standards, and the new named USB standard changed the original USB1.1 's title to "USB 2.0 Full Speed", while changing the original USB2.0 to "USB2.0 high-speed "(High-speed version), and at the same time announced the new logo. Although at present USB1.1 and USB2.0 like, all have USB2.0 prefix, easy to let merchant drill word loophole, but everyone in buy wireless card when must pay attention to its behind full speed (high speed version) and high-speed (express version) difference.

② motherboard support is key to using the USB2.0 wireless card, especially for readers who are still using PIII or even a PII grade laptop or desktop computer.

To identify whether your computer supports and has a USB2.0 socket. You can turn on Device Manager → Universal serial bus in turn, if you have the enhanced (enhanced) USB Host Controller option (you will also see two other USB controllers, These two controllers make the USB1.1 device backwards compatible), which proves to be able to support the USB2.0 device (requires the installation of a USB2.0 driver). Otherwise, the high-speed wireless network card can only be transmitted at a maximum of 12Mbps (actual no more than 6Mbps) USB1.1. You should also be aware of this when using a USB hub, and be sure to choose a USB2.0 hub.

USB1.1 speed, the theory is the largest 1.5mbyte/s, but in actual transmission, can exceed 1m/s USB device not much, MP3 is no exception, generally only hundreds of kb/s.

As for USB2.0 full speed (full-speed), I think is most worthy of attention, because, USB2.0 full speed (full-speed) MP3 in the second half of 2004 more than ever, from the name, quite imposing, USB2.0 full speed, as if USB2.0 high speed bad Of But in fact, it is reported that the USB association renamed the USB Standard: The original USB 1.1 was changed to USB 2.0 full speed, while the existing USB 2.0 is changed to a USB 2.0 high-speed (high speed version).

In practical applications, USB2.0 full speed (full-speed) is not as loud as its name. Far from reaching the maximum speed of the USB1.1 specification, the actual speed difference with USB1.1 is not obvious.

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