The not-so-universal serial bus
May 19, 1998
Web posted at 4 p.m. EDT
by Bob O'Donnell
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
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
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
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.
Bob O'Donnell has been writing about, talking about, analyzing,
testing, and using computers and other high-technology equipment for
more than 13 years. He also hosts "O'Donnell on Computers," a weekly
computer talk show heard every Saturday from 10:00 a.m. to 1:00 p.m.
on San Francisco Bay area radio station KSFO (560 AM) and on the Web
via RealAudio. In addition, he is the computer expert on the "Meeting
the Challenge" television program.
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