A USB is intended to enhance plug-and-play and allow hot swapping. Plug-and-play enables the operating system OS to spontaneously configure and discover a new peripheral device without having to restart the computer.
As well, hot swapping allows removal and replacement of a new peripheral without having to reboot. There are several types of USB connectors. The USB 2. A keyboard or mouse are common examples of a type A USB connector. A type B USB connector is square with slanted exterior corners.
It is connected to an upstream port that uses a removable cable such as a printer. The type B connector also transmits data and supplies power. Some type B connectors do not have a data connection and are used only as a power connection.
Micro-USB cables are usually used for charging and data transfer between smartphones, video game controllers, and some computer peripherals. Micro-USB are being slowly replaced by type-C connectors, which are becoming the new standard for Android smartphones and tablets.
A Universal Serial Bus USB is basically a newer port that is used as a common interface to connect several different types of devices such as:. It is designed for easy installation, faster transfer rates, higher quality cabling and hot-swapping.
It has conclusively replaced the bulkier and slower serial and parallel ports. Their objective was to make it easier to connect peripheral devices to a PC and eliminate the excessive amount of connectors. The USB controller on the host the computer with a built-in USB port or a USB serial card manages communication between the connected USB devices by using a mechanism called transfer queuing, whereby devices make a request to the controller, which queues the request and responds to it in a first-in, first-out FIFO manner.
Requests made by USB devices are typically one of the following:. All USB requests are handled by the host controller, which obtains and sends the necessary control information or data to the device.
USB cabling is 4-wire cabling that typically uses a gauge twisted pair for data transmission and a gauge untwisted pair for carrying power to the devices. Cabling is available in both shielded and unshielded forms. The following table shows the pinning types for USB cabling. USB supports two speeds, which depend on the type of media used to connect peripherals:. USB 2. USB 3. It provides two unidirectional data paths for receiving and sending data at the same time.
Following the release of USB 3. Dell began including USB 3. Today, many devices use the USB 3. Each version of USB port is backward compatible and forward compatible , meaning it can support any version below or above its current number. For example, devices designed with USB 1. However, it should be noted that devices with lower versions run at their native transfer speeds even though USB 3. Similarly, if you connect a USB 3. USB cables are available in multiple lengths, from a few inches to over 16 feet.
The maximum length of a USB cable is 16 feet 5 inches 5 meters for high-speed devices, and 9 feet 10 inches 3 meters for low-speed devices. These maximum lengths are due to data transfer timing and the risk of data loss if using longer cable lengths.
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