Back in the day (my son's favorite saying if it is over two years ago)
computers came
with a parallel and a serial port for connecting
external devices (besides
keyboard and video). Parallel was for the printer and a couple of specialized
devices. Serial was for things like modems, EPROM burners, or sometimes a mouse.
Newer computers have
USB ports that replace both the Parallel and the Serial
ports. The best of both worlds have all three. My laptop is brand new, no
parallel, no serial, no mouse, or keyboard ports but it has three usb ports, and
surprise one is on the front of the computer, amazing.
This is kind of ok, most devices are going usb anyway, but
if you still have the
old devices you will have to install a card with the appropriate port to utilize
it.
So what does this mean to you? One thing is how many ports do you have? How many
devices do you want to connect? Older devices were the 1.1 standard the newer
are 2.0. Do you want to be able to boot your system from your usb floppy or
cd-rom, how about your flash drive?
Lets look at the standards first.
1.1 is the original ISO (International Standard Organization) for USB. The
standard specifies how the usb protocol will be implemented and what is expected
from devices utilizing the standard. The main factors here are the type of
connector used on the computer and the device and the connection speed.
(Note: the original specification did not have a provision to power the device
down while the computer was powered up, to disconnect with out damaging the
device or the computer you had to power every thing down.)
2.0 is an upgrade of the ISO standard, that specifies a faster speed for the
device, adding a provision that the computer could turn the device off (power it
down) before disconnecting, this also allowed for the user to connect the device
while the computer was powered up. Very handy.
Connecting and Disconnecting USB Devices
Most of the 2.0 standard software is built into the drivers that are installed
by the OS when it is installed, although some devices have their own drivers
when you purchase the product. So the only time you have to worry about 1.1
version USB is when you connect the device and then want to disconnect it while
the computer is powered up. Windows XP has an icon in the system try that looks
like a arrow pointing down over a green card, this is the "Safely Remove
Hardware" program. If you open it up any device that the OS can power down is
listed here. There are a couple of devices that will be listed here that are not
usb devices, laptops will list a CD/DVD that is considered docked, some laptop PCMI cards will be listed. If you select a device and click on the "stop" button
you will get a message that the device is safe to remove, but if it is a 1.1
standard it may not be powered down! Other times you will get a message that the
device can not be safely removed, there may be a file open on the device or the
software is telling you it can not power down the device. Either way do not
disconnect the device you could damage the device and or the computer. In this
case you will have to power everything down to disconnect it.
