USB Matters

Years ago we used to have parallel ports, serial ports, scsi ports and goodness knows what else. Things are a lot cleaner and more straightforward now that most things connect to computers via a “USB port”. USB stands for “Universal Serial Bus“, strongly suggesting that this is a method for connecting all kinds of things via the same socket (or “port” as computer people call them).

Nowadays, we take USB ports and connections for granted, but there are a few things that it’s worth pointing out for the benefit of normal human beings (eg my own computer clients) who need to use them every day but don’t normally take any notice of them.


USB3 Ports
USB 3 ports are blue inside
USB3 is the latest “incarnation” of USB connections. The main improvement that we will notice is that USB3 is much faster. See this Wikipaedia article for more details. USB3 hasn’t yet completely replaced USB2 ports on new computers, but where they are present there seem to be one or two of them on a computer that also has one or two USB2 ports. As always with these things, I think we can get what my chemistry teacher used to call “delusions of accuracy” if we measure these things to the nth degree. However, I can tell you that transferring significant amounts of data (say 5gb or 10gb) to an external hard drive is definitely a lot faster with USB3 than USB2. Note, though, that it’s not enough to have a USB3 port on the computer: the destination (eg an external drive) also has to support it for the speed to be improved. It’s easy to tell which ports are USB3 as the inside of the port is blue (compared with black for USB2) – see photograph. USB3 ports are “backwardly compatible” so any USB2 device can be plugged into a USB3 port (and this will work at USB2 speed).

USB Sleep and Charge

Some computers now come with one or more USB ports that keep the power on when the computer is asleep or switched off. This means you can plug in a smartphone – or similar device that re-charges via a USB port – without having to keep the machine switched on or even plugged in (if it’s a laptop with its own battery connected).

Cables with Double Connectors

USB Cable With Double ConnectorHave you ever bought a USB-connected device that came with a cable that has two connectors at one end (see illustration)? If so, you may be wondering what the “spare” connection is for. Well, it’s just to ensure that the device is getting enough power from the computer it is connected to. Simply connect both of the “double ends” to ports on the computer. If you only connect one of the pair and the device doesn’t work then try the other. If it still doesn’t work then you definitely need both ends to be connected to get enough power to run the device. That can be a problem on laptops with limited USB ports. My old Samsung Q35 laptop only had 2 usb ports and they were on opposite sides of the case so the only way to connect power-hungry USB devices was to attach a USB extension cable to one port so that both ends of the USB cable were within reach. A bit messy and inconvenient.

Problems with USB Connections

The word “universal” suggests that you would expect a USB connection to work in any USB port. Generally speaking that’s true, but if you find that a USB-connected device doesn’t work it is definitely worth trying it in a different port. The port that didn’t appear to work for the first device may work with another device connected to it. I think this is all to do with the amount of power available to run the device and that some ports may be able to deliver more power than others (due to their position on the motherboard?) I’m not completely sure about the technicalities of this but I’m absolutely sure that it’s worth trying to swap them around. If you’ve got a lot of USB ports with lots of devices and you need to dis-connect them all (to pull the computer out from under a desk, for instance) then it’s well worth noting which device was connected to which USB port so that you can be sure of putting them back in the tried and tested configuration. When working on my own computer clients’ machines, I will sometimes take photographs of the connections before pulling things apart.

USB Ports Too Close Together

USB ports are often sited very close to each. This is usually OK if the connectors are of the standard size but some devices – such as wireless USB receivers and so-called “dongles” – are just too fat to place next to connectors in adjacent ports. The easiest solution in such situations is to buy one or more short USB extension cables and connect the fat device via the extension cable. The cheapest place to get things like this is at a computer fair but I wouldn’t expect normal people to frequent such places so you’ll have to bite the bullet and pay Maplin or PC World prices (or cadge one from me when I’m with you providing computer support or advice).

USB Hubs

4 port USB hub
4 port USB hub
These devices plug into a USB port and then allow you to plug two, four, or even more USB devices into them. In most cases they work fine, but try to avoid connecting external hard drives or CD/DVD drives into a hub unless the hub has its own power supply. This is because the computer may not be able to deliver enough power to the device if it’s going through a hub (that may also have other devices taking power from the same USB port). USB devices that are definitely suitable for connection via a hub include mice, keyboards, and cameras.