Although it was just over three years old, my old computer was fast approaching the end of its useful life. The processor was not upgradeable, the monitor was beginning to show signs of fadeout, and the keyboard had several keys that stuck intermittently. I had typed many thousand of words on it, so I can't really complain too much. Nevertheless, it was time to upgrade to a newer model.

The notebook I selected came with many new goodies, and like most modern systems it supports USB (Universal Serial Bus) for connecting peripherals to the main unit. USB is supposed to eliminate the need for fiddling with interrupt settings, changing jumpers, and other problems associated with adding new hardware to a typical computer. USB supports hot-swapping, meaning you can connect and disconnect devices from the USB port without having to reboot the computer -- a huge advantage when you only require a device to be occasionally active (such as a CD-RW burner).  

SIGPC readers may remember my experiences with SCSI in the Summer of 1998, when I was attempting to connect an external hard drive to my notebook computer. This time round, I was trying to connect virtually every peripheral I have via USB. I can report that using USB is far easier than using SCSI. But USB is still not perfect. 

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Hubs

Like SCSI, USB lets you chain multiple devices on the same serial connection.. To connect more than a single device to a USB port, you first connect a USB cable (such as that shown on the right) from the computer to a hub. You can then connect up to 127 devices on the same USB line, chaining hubs together as needed. Each USB peripheral in the chain is limited to 100 milliamps of power; if it requires more, it must provide its own power supply.  

This approach works fine, except that it can become quite expensive. A 7-port USB hub such as that pictured here costs about $120 in my area. The hubs I use are stackable, so you can serially connect several of them together. The result is that most of your peripherals can be connected to your main computer using just a single cable. If your computer is a notebook computer, as mine is, this is a great timesaver. When I move the computer from home to work, I just need to plug in a single cable to reconnect it with all the peripherals available at each location. In essence, the USB hub serves the same role as a docking station for a notebook computer, but it is more flexible and less costly.

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Legacy Peripherals

You can get special multipurpose hubs that offer ports other than standard USB, such as USB to serial, USB to Ethernet, and USB to parallel. In theory, this approach lets you keep using some of your legacy equipment, such as scanners, and still enjoy the convenience of USB. In practice, its not this easy.

By far my biggest headache was trying to get my old printers connected to my new computer. The printers I had rely on the parallel port to connect to the computer, and since my computer did not have a parallel port (except on the port replicator), I wanted to connect the printers to the computer using the USB hub. The first approach I tried was to use a special USB-to-parallel cable. This means you don't need a special USB hub, just the converter cable and driver software. I tried products from two different vendors that purported to do this, but was never able to get it to work properly. Every time I rebooted my computer, the operating system kept asking for a new printer driver, as if it was rediscovering the existence of the printer every time. 

I eventually gave up and purchased a new USB printer for home use. For office use, I purchased another hub that had the USB-to-parallel port converter built-in. This solution seems to work fine. I still don't know why the first cable-based solution didn't work, and neither did either vendor, even after repeated debugging sessions with their technical support personnel. 

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What's Next?

USB supports connections running at up to 12 Mbps. This is fast enough to support many devices, such as a typical Ethernet connection. However, this is not quick enough to support Fast Ethernet connections, or other peripherals that require higher-speed links, such as digital cameras. For this type of bandwidth-intensive application, another approach must be used.

One choice is SCSI, the traditional serial connection technology for computer peripherals. A more modern alternative is IEEE 1394 (also known as "FireWire" for Apple machines, or "i.Link" for Sony devices). 1394 is primarily used to connect digital cameras to computers, although there are 1394 external disk drives too. 1394 supports 400 Mbps connections, making it is much faster than USB -- at least for now. When USB 2.0 devices arrive (likely in the second half of 2000), they will offer speeds approaching those of 1394: 360-480 Mbps. Not to be outdone, 1394 has plans to support 800 Mbps connections in its next release.

At the moment, USB seems to have more industry support than 1394. As with most technologies, it is not necessarily the most sophisticated products that win, but those with the most momentum. In any event, consumers will benefit from the increased capabilities that such peripheral connection technologies provide. If only the quality of the software kept pace with the speed of the hardware ...

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