What is USB – Universal Serial Bus?

USB or universal serial bus has been around since the mid-nineties. Although the technology is ubiquitous, people are still confused by some USB types and limitations. I’ll admit it can be confusing, but I’m glad I no longer have to wrestle with parallel and serial ports. I’ll explain the differences and tell you how to find out which version you’re using.

Benefits of USB

Before USB, connecting devices to your computer could be a nightmare. It was common to have devices conflict with each other. You were also constrained by how many ports your PC had unless you bought more equipment. You might have to unscrew one connection for a printer to make room for an external backup device.

The big benefit to USB is you can easily connect devices to your computer. Although there are different cable types, it’s easy to know which end to use. Once a connection is made, Microsoft Windows recognizes the device. With some devices you may have to install a software driver.

Another advantage is you can swap USB devices in and out without having to reboot your computer. Technically, you can run 127 USB devices. If you want to run that many devices, you have a plethora of devices ranging from flash drives to digital cameras.

The USB cable can also provide limited power to a device although larger devices such as a USB printer still require more power. Some manufacturers have leveraged this feature and released USB-type devices that have nothing to do with a PC and data exchange. These tend to be novelty items like personal fans and coffee mug warmers.

Recognizing USB Ports & Cables

One byproduct of industry standards is you often get a logo. The logo helps consumers identify ports and cable connections. The primary USB logo is called the “trident”. You can see and feel this logo on the top side of the cable that plugs into your PC. See the circled item in the thumbnail below.

USB trident logo USB cable connector picture

(Pictures from WikiPedia)

As the picture above shows, there are different end plugs. USB cables have a USB Type “A” receptacle end that plugs into your PC. This is a “universal” plug type since it fits all computers that have a USB port. Where they differ is in the other end plug. The difference is usually because of the size of the device you wish to connect. For example, there are “mini” and “micro” plugs that are used for tablets, digital cameras and phones. These 5 connector end plugs handle most USB connections.

One exception is Apple which uses a proprietary cable to connect devices. Even the same manufacturer may use different end plugs. As example, it would be more convenient for the user if Omron used the same USB cable for their pedometer and blood pressure cuff. And don’t expect the manufacturer to always supply a USB cable.

Another item you should be aware of is your USB cable length. The cable should be less than 5 meters. If you need to connect a device to your PC that is further away, you’ll need to insert another device such as a hub. Don’t assume USB 1.1 cables will work with USB 2.0 devices. It depends on the manufacturer.

USB Versions and Data Rates

Your computer should have ports using one of the three USB versions listed. These are: USB 1.1, USB 2.0 and Wireless USB. Although these ports have similar looking receptacles, they offer different data rates. It’s also possible to add USB 2.0 ports to your system.

The USB 1.1 spec called for devices to be able to transfer data at a maximum rate of 12 megabits per sec. There were two different data rates. The “low speed” was for 1.5 megabits per second. Items such as your mouse and keyboard can run at these low speeds. The “full speed” was 12 megabits.

Around 2000, USB 2.0 was released and new computers started using this current version. Although it can provide “low-speed” and “full speed” data rates, it supports data rates as high as 480 megabits. This new rate is called “Hi-Speed”. The key point to remember is while “full speed” was the fastest for USB 1.1; it’s nowhere near “hi-speed”.

In May of 2005, Wireless USB was introduced. Version 1.1 is found on some newer notebooks offered by companies such as Lenovo, Dell and NEC. As the name suggest, you don’t need cables. Instead, you have a USB dongle that plugs into your USB port and it uses an ultra-wide band radio frequency. The data rate is comparable to USB 2.0 if the device is within 3 meters. This data rate does decrease as you move further away from your computer. Certified Wireless USB also offers the added feature of AES 128 bit encryption.

This is a standard that is also evolving. The current version is USB 3.0, which can transmit at 5.0 Gbit/s and this will increase to 10.0 Gbit/s

One item that may cause confusion is other USB logos people see. These relate to a certification process by the USB-IF (USB Implementers Forum). This group test products to make sure that they are compliant with the current specification. Companies can build a device to a USB spec, but they don’t always have to get certification. Many manufacturers spend the time and money to have the device tested. These certified devices are more apt to “play nice” with your system and other devices. In the case of wireless USB, I would want a device that has been certified because it uses encryption.

An example of the certified USB logo is below. There are similar logos for Hi-Speed USB and Certified Wireless USB.


(Picture from WikiPedia)

Which Version of USB does my PC Use?

Many people have computers which have USB 2.0 ports. However, there are a number of systems that have USB 1.1 ports. Although 2.0 ports are backwards compatible, you’ll probably have issues if you try to connect a USB 2.0 peripheral into your USB 1.1 port.

To find out which USB version your PC uses,

  1. From the Start menu, select Run…
  2. In the Open: text field of the Run dialog, type devmgmt.msc
  3. Click OK
  4. In the Device Manager dialog, scroll to Universal Serial Bus controllers and click the + sign.

If your listing shows Standard Universal to PCI to USB Host Controller, you have USB 1.1

If your listing shows Standard Enhanced Universal to PCI to USB Host Controller, you have USB 2.0

If your listing shows  USB 3.0, you have version 3.0

If you’re not using USB devices, I would encourage you to try them. They really can make things easier. I imagine we’ll start to see more wireless USB devices as well. Just remember to check your system to know which USB version you’re using and if you need to also get new USB cables.