May 18, 1998
The Not-so-universal serial bus
By Bob O'Donnell
I'm a big believer in the value of anything that makes computers easier to set up,
install and use. So I've long been interested in the notion of the Universal Serial Bus,
or USB, which aims to make the process of adding
peripherals to your computer as simple as possible.
As you probably know, USB offers the promise of as many as 127 devices daisy-chained
off the USB ports on the back of your desktop or notebook computer. It can also provide
power to those devices -- which gets rid of the need for bulky AC adapters -- and it
supports hot-plugging, which means you can simply connect the device to your computer
while your PC is turned on and start using your new peripheral almost immediately.
Finally, its best trick of all is that it can do all this while only using a single
interrupt request for the USB controller (which is built into the chip set of most newer
computers).
USB ports have been standard on most desktop PCs for nearly a year and a half now and
have started showing up on notebooks since around the first of this year. Even Apple
recently got into the act by announcing that its slick new iMac will be the first of many Macintoshes to also
feature USB ports.
On the PC side, USB ports sat idle for quite a while because although Microsoft added
USB support to Windows 95 in OEM Service Release 2.1 around the same time they started to
appear in volume on desktops, no USB devices were available to take advantage of them for
quite a while. Now that USB devices have started to appear in quantity, it appears that
the bus may not be as "universal" as originally hoped. Interestingly, however,
it is more universal than Microsoft's marketing for Windows 98 suggests -- but I'll get to
that in a bit.
First, according to some research I've been doing on Intel's Web site, there are two
different types of USB controllers and not all devices work with all controllers. Intel's
Create & Share USB video camera, for example, works on computers with Open Host
Controllers but not Universal Host Controllers. (See USB
Troubleshooting Notes for more.) There is no solution to this problem from what I can
tell -- the camera just won't work properly. Other USB devices apparently have similarly
frustrating limitations.
Also, it turns out that USB's power capabilities are rather limited unless you attach a
powered USB hub to one of your computer's USB ports. If you hook together more than a few
low-power devices or try and attach even one power-hungry peripheral to your PC's USB
ports you'll probably need to use AC power adapters after all, which is kind of
disappointing. This isn't exactly a secret, but very few people seem to know about this
limitation. It's just another case of the computer industry setting expectations that
don't quite match reality.
In a somewhat related way, Microsoft's marketing for Windows 98 seems to imply that you
need the latest OS to take advantage of USB. The truth is, however, Windows 95 has had
built-in support for USB since OSR 2.1 and USB devices can and will work under Windows 95
B (or OSR2). Since OSR 2.1 has been around about as long as PCs have had USB ports, most
people who will be interested in adding USB devices (i.e., the ones who have USB ports on
their computers) already have the version of the OS they need. And even if they don't, USB
peripheral vendors can ship both the USB system drivers and their own device-specific
drivers along with the USB device. So, as with most other hardware add-ons, users simply
have to install the drivers when they attach the device to their PC.
Under Windows 98, the difference is that the OS will have a bunch of device-specific
drivers built-in. This means that certain USB devices will truly be plug-and-play because
the user won't have to install anything. Of course, drivers that don't ship with Windows
98 or that are updated down the road will still have to be installed anyway, so I really
don't think this is such a huge advantage. The implications that Windows 98 is somehow
"necessary" for USB (or digital video disc, for that matter) is just another
classic case of Microsoft FUD (fear, uncertainty and doubt) mongering.
Ultimately, I think USB will prove to be a great addition to the PC market and a
favorite among end-users, but it would sure be nice to get a more complete disclosure on
what it can and can't do and what's really needed to make it work.
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Copyright 1998, by InfoWorld Publishing Corp., a
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