- By Jeff Field -
In the past couple of years, USB devices have started to catch on in popularity. They're nowhere near the revolution people once claimed USB would be, but USB devices have, for the most part, replaced parallel and serial ports on todays PCs. However, USB has its faults, one of which is that if you have more than a few devices that require a lot of bandwidth on the chain, they will start to slow down.Most PCs have two USB ports and those are both on one controller, leaving the PCs only 12 MB/second for all USB devices. This is particularly annoying when using a USB CD-RW drive, because it can cause bad burns. What can you do about this? You can either disconnect some of your other USB devices when you are using the devices that are more bandwidth hungry, or you can purchase a USB expansion card which gives you more USB ports at the cost of a little money and a PCI slot. I am reviewing two such cards today, both from Belkin, a maker of many PC and Mac accessories.
The cards are relatively simple, just small PCI cards with two or four PCI ports on the back. The two-port PCI card is powered by an Opti USB controller, and both ports share the same 12 MB/sec bandwidth. The four-port PCI card is powered by a Lucent chip, and on the four-port card each port gets its own 12MB/second connection -- called "QuadraBus" technology by Belkin -- so devices on the different ports do not share bandwidth. Whether your PC has the normal two USB ports or not, this is a significant boost because in most cases the ports share bandwidth. This card gives you five times the usual USB bandwidth, certainly nice for someone who has a lot of USB devices that are bandwidth-hungry.
Running under Linux
The cards are supported "out of the box" by some versions of the Linux kernel. You simply need to make sure the 'usb-ohci' module is either compiled into the kernel or loaded as a module, and these cards will be detected as a normal USB controller. Once detected, they are fully functional USB ports just like any other. I connected a USB mouse and a USB Zip250 drive to the card without incident, it performed just like any other USB controller. In fact, at one point I had both of these cards in my test machine plus the default controller on the motherboard. This caused no problems, and allowed me to have a total of six USB controllers in one machine. While this does not have many practical applications, it certainly has some novelty uses, like hooking up two mice.
The documentation that comes with the cards is very simple and includes information on how to physically install the cards and how to get them working with Windows and MacOS. This information is of little use to Linux users, but the cards really do not need a lot of explaining.
If you are in the market for USB expansion cards, take a look at these offerings from Belkin. I highly recommend the four-port USB card (part number F5U006-UNV) over the two-port (part number F5U005). The four-port card costs $45.00 (the lowest price I could find using Google) which is only $15 more than I found the two-port for on Pricewatch, and you get two more ports and the advantage of each port having its own dedicated bandwidth. If you are looking to add ports to a system with no USB ports but with free PCI slots, this is certainly a more economical (both in time and money) solution than buying a new motherboard. The cards both run flawlessly under Linux.
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