| Universal
Serial Bus (USB) is an initiative originally proposed by Intel,
Compaq, and Microsoft back in 1995. The primary purpose of USB was
to make adding devices and peripherals to the PC easier. And to
centralized all the I/O connectors in the back of a typical PC.
Currently, there are connectors for keyboard, mouse, printer,
joystick, serial ports, etc. Why not just have one universal
connector in which user can connect all their devices?
In addition to standardizing on one port, the USB design also
have the following advantages 
:
Speed - The maximum bandwidth of USB is 12Mbps, which is
faster than most ethernet cards. Compare this to the maximum speed
of a typical serial port, which is 115Kbps
.
- Hot Swap - USB is mainly designed for external devices.
Wouldn't it be nice to add and sremove devices to your system
without having to power it off and on? USB allows user to add a
device while the system is turned on; USB will then
automatically enumerate the new device, load the driver, and
allow the user to use it
.
- Flexibility - With traditional serial ports, users were
limited to the type of device they can add. With USB, there's
almost no limitation. A USB device may be almost anything:
mouse, joystick, modem, printer, scanner, etc. Also, a user can
add up to 127 USB devices per system. Of course, practical
limitations may reduce this number, but it is still better than
having the standard "two serial ports per system."
So you're thinking, "Hey, this is a great idea! But if
USB was introduced in 1995, where are all those wonderful USB
devices today?" USB suffers from the classic
chicken-and-egg problem. Peripheral makers were waiting for
system manufacturers to integrate the USB port into their
system, and PC makers were waiting for peripheral designers to
create USB devices first. And to compound the problem, Microsoft
didn't release USB drivers for Windows 95 until late 1997. If
you've purchased a new computer system in late 1997 or now,
chances are you'll have two USB ports with the USB drivers
loaded
.
USB devices should take off once Windows 98 hits the market.
For more information about USB, see the following links
:
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