If you purchase a computer today you will most likely find it has at least one USB port of one version or another. What are the various kinds of USB ports, and what are their advantages and disadvantages?
What is USB? USB stands for Universal Serial Bus, and is an industry wide standard connection that can transfer data, connect peripherals, and provide power to external devices. USB has been around since the mid 1990’s and has been through several iterations (versions 1.0, 2.0, 3.0 & 3.1).
What Versions of USB are Used Today? USB 1.0, 2.0 and 3.0 are all in common use today. The latest version, USB 3.1 (introduced in January 2013) is just starting to be used.
What are the Common USB Connector Types? There are six common types/sizes of connectors, Type A (standard, mini, & micro), and Type B (standard, mini, & micro).
Type A standard connectors are almost always used on the computer side, and sometimes on the device side, while the smaller mini/micro A and Type B connectors are usually found on the device side (such as with printers, scanners, cameras, etc.). There are also some proprietary non-standard USB connectors (for example those used with the iPhone or iPad).
The latest new connector is the Type C. It is used with USB version 3.1, and has the advantages of small size, low cost, greater power transmission, and reversibility. Apple’s latest MacBook uses the Type C cable for everything (including charging the machine, along with a charging unit).
Power Transmission: Versions 1.0 & 2.0 can transmit 500mA of power to a peripheral, while versions 3.0 & 3.1 transmit 900 mA. Version 3.1 with the Type C cable has even greater power transmission capabilities.
Maximum Length of a USB Cable: Versions 1.0 & 2.0 specify 5 meters (~ 16 feet) as the maximum length, while versions 3.0 & 3.1 are silent on the topic. Most experts say that you should limit your length to 3 meters (~10 feet). (Tip: You can extend this distance by inserting powered USB hubs at intervals of 5 meters or less).
Conclusion: USB 3.0 & 3.1 are huge improvements over previous versions, especially with the new Type C cable. There are three other connection standards you should be aware of, Firewire, Lightning (Thunderbolt on the Mac) , and eSATA. By comparison Lightning operates at 10-20 Gbps, eSATA at 6 Gbps, and Firewire 3.2 Gbps. Firewire (mainly used by Apple) seems to be on the decline, however I suspect Lightning, and eSATA will still be used on high performance machines for some time. My guess is that USB-C will eventually become the dominant way we hard wire connect our machines.