Continuing our ongoing examination of the components of a standard personal computer, we?re going to look today at USB: What it stands for, what it does, why we want it.

Previously, in computers, all outside communication was done via the printer-port (or parallel port (pink/purple colour on the back of your computer), or via the COM port, which is about the same size as a VGA port, but it?s a socket not a plug. The issue with these two connection technologies, was that they were, at least by today?s standards, extremely slow.

In the 1990s, the advent of faster processors and peripherals, required a step-change in connection performance: Enter USB ? Universal Serial Bus, which has allowed further leaps in peripheral technology, such as digital cameras and key-drives, and allowed older peripheral technology, such as network adapters, to be reconfigured as USB connectable, making them easier to use by us earthlings.

But there?s more to USB than that: First, it?s a Plug and Play (PNP) technology, which means, unlike previous technologies, you can usually go along and simply plug a new device into a USB port and the system will detect it and install it: Another huge leap forward in usability. Second, up to 127 peripherals can share one port at any one time; that?s right 127 peripherals ? making it a very efficient connection technology.

The USB standard, allows peripheral manufacturers to easily accommodate USB connection on their product. Its small physical size has enabled companies such as mobile phone manufacturers to incorporate USB on phones, allowing users to synchronise telephone address books, calendars and all manner of data between phones and computers.

The problem for us is that typically a computer will have a maximum of six USB ports on it ? two on the front panel, and four on the back. As more and more peripherals are converting to use USB technology, we?re going to run out of ports pretty fast, aren?t we?

Well, no. You can purchase what is called a ?USB Hub?, which is a little like a power extension cable ? it plugs into one port and has on it up to four others. With six main ports on your computer, to each of which you can attach a USB Hub, that totals 24 peripherals that you can now attach to your Universal Serial Bus. Not many of us, I would imagine, would be looking to attach more than that to our systems at any one time.

There are just a couple of issues with USB. First, my experience with USB tells me that sometimes it kind of just ?loses its way? ? that is, suddenly stops behaving correctly.

A connected USB peripheral can be working fine, left alone for a couple of hours, and then when you return to start using it, not work. There is no reason for this that I can find.

My instinct tells me that something times-out, but, as I am not a USB protocol specialist and as with all peripheral connection issues, simply unplugging it and plugging it back in will usually fix it.

If not, restarting your computer will almost definitely resolve it. Annoying as this is, it is nothing like as complex a resolution procedure as we would have had to follow, say, ten years ago.

Second, sometimes USB peripherals will work in some USB ports and not in others. Again, I can find no believable explanation for this, and, again, plugging the peripheral into another port, or swapping it with another connected peripheral will usually resolve it.

Thirdly, I have found that USB peripherals requiring lots of bandwidth ? by that I mean peripherals that need to send and receive huge amounts of data on USB will tend to behave better if connected on a dedicated USB port.

What I mean here is that ?fast? peripherals, such as digital and video cameras, should not be connected to your USB port via a USB hub.

If they are, then they will be sharing the available bandwidth with other peripherals, jostling for position and obtaining only the bandwidth that is available, and not in use by other peripherals.

Many ?fast? peripherals will simply give-up trying if connected to a USB Hub, so my advice is to connect these types of peripherals directly into a port on your computer, and not via a USB hub.