Universal Serial Bus (USB)

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USB is a plug-and-play interface that allows a computer to connect with components and other devices.  USB-connected devices cover a wide range of categories, from keyboards to music players and flash drives.

USBs are also used to transmit power to certain devices, such as smartphones and tablets, as well as to charge their batteries.  USB version 1.0 was first released in January of 1996, and was quickly adopted by companies like Compaq, Intel, and Microsoft.

USB Ports Location

All modern computers have at least one USB port.  Here are the typical locations where you’ll find a USB port on a computer:

  • Desktop computer – typically has 2 to 4 ports at the front and 2 to 8 ports at the back.
  • Laptop computer – generally has between 1 and 4 ports on the sides of the laptop.
  • Tablet – most often has 1 port which is the same as the charging port, though some may have an additional port at the side.
  • Smartphone – uses a USB port to charge the battery (either at the top or bottom of the phone), which can also be used as a standard USB port when the battery is not being charged.

USB Devices

Millions of different USB devices can be connected to the computer.  Some of the most popular USB devices are categorised and listed below:

  • Audio
    • Speakers
    • Microphone
  • Human Interface Device
    • Keyboard
    • Mouse
    • Joystick
  • Image
    • Webcam
    • Scanner
  • Printer
  • Mass Storage
    • Thumb drive
    • Digicam
    • External drive

USB Transfer Speed

  • USB 1.x provides a transfer rate of 12 Mbps and is capable of supporting up to 127 peripherals.
  • USB 2.0 provides a transfer rate of up to 480 Mbps or 60 MBbs. It is also known as high-speed USB, and was introduced in 2001.
  • USB 3.0 provides enhanced speed and performance in comparison with USB 2.0, including improved power management and bandwidth. It is also known as SuperSpeed USB, and was first made available in November 2009, even though the first certified devices weren’t available until January 2010.
  • USB 3.1 provides a transfer rate of up to 10 Gbps. It is also known as SuperSpeed+ and was made available in July 2013.  It is the latest version of USB, and is mostly used by many devices now due to its enhanced performance and speed.

USB Connector Variations

USB connectors come in many shapes and sizes, such as:

  • Standard
  • Mini
  • Micro

USB Cable Length

USB cables come in multiple lengths, from around 3 feet to just over 16 feet in length.

Device USB Cable Maximum Length (in feet) USB Cable Maximum Length (in meters)
High-speed devices 16 feet and 5 inches 5 meters
Low-speed devices 9 feet and 10 inches 3 meters

These maximum lengths are set to take into consideration data transfer timing, as well as the risk of losing data when transmitting through longer USB cables.  However, USB hubs can be utilised to join two USB cables together, thus extending the distance between the two devices being connected.

USB Cable Types

Since there are different transfer speeds for USB, there are also different types of USB cables, designed specifically to work with those transfer speeds.

  • USB 2.0 cable is compatible with a device using USB 2.0
  • USB 3.0 cable is compatible with a device using USB 3.0.

There are USB extension cables that can join to one end of a USB cable to extend the length of the cable.  It is not recommended to use the extension cables beyond the maximum length limit, unless you’re using a USB hub.

USB Flash Drive

A USB flash drive is a plug-and-play storage device.  It is also known as a USB stick, USB thumb drive, or pen drive.  It is portable and lightweight, and has largely replaced CDs for storage and backup purposes.