USB Port questions...

[markus4412]

Hi, through Windows XP's device manager, I see I have four 'USB Root
Hub' devices. These correspond to the four usb ports on my laptop, 3
on the right of the machine and one on the left.
When I right click on the devices, and choose 'Properties', I can click
'Power' and for each of the right USB hub devices I'm told there are
'2 ports available'., for the left side one i'm told there are '6 ports
available'

After fiddling though, it seems that two of the actual external usb
sockets on the right of my laptop seem to correspond to one of the usb
hubs - if i put my mouse in one socket, and my bluetooth dongle in the
one next to it, they both show up on the same 'usb root hub' devices'
Power page, and there are no more 'ports' available on this one.

The third external usb socket is there on its own, but also supports
two ports - would I need a hub to access these, or Is there some kind
of splitting device to turn one socket into two that might be cheaper?

Again with the left-hand external usb socket - this appears to support
6 devices (at up to 500ma per device), would I really need a hub for
this or can I again just get a splitter of some kind?

Finally, there is a fourth 'usb root hub' device listed, but there is
no physical usb port that corresponds to this; is this just due to the
generic way some laptops are made and it simply hasn't been connected?

Hope that made sense!

Mark.

 

[Barry Watzman]

The internal operation of USB controller chips is incredibly complex.
For example, take the Intel ICH 5 chip. It has, internally, four
two-port USB 1.x controllers AND one eight-port USB 2.0 controller and
it has external connections for eight USB sockets. But the assignment
of the sockets to the five internal controllers is dynamic, and can
change while the machine is running (e.g. if you unplug a USB 1.x device
from a USB physical port (socket) and plug in a USB 2.0 device (or
vice-versa), the port (socket) can "move" from one controller to
another). Don't try to figure it out, just use it, as long as it is
working.

 

[Joseph Fenn]

The internal operation of USB controller chips is incredibly complex. For
example, take the Intel ICH 5 chip. It has, internally, four two-port USB
1.x controllers AND one eight-port USB 2.0 controller and it has external
connections for eight USB sockets. But the assignment of the sockets to the
five internal controllers is dynamic, and can change while the machine is
running (e.g. if you unplug a USB 1.x device from a USB physical port
(socket) and plug in a USB 2.0 device (or vice-versa), the port (socket) can
"move" from one controller to another). Don't try to figure it out, just use
it, as long as it is working.

Speaking on that same subject the P4 Laptop I bought has only one
USB port on the back of it, and no firewire port at all. So I
bought a 4 port belkin hub and its short cable to connects it to the
laptop and though it works ok with 3 drives connected to it,
A, H and a outboard burner, It always tells me that MY usb
devices are working and detected okay, but they are working at
SLOW speed mode. The Belkin card said it was a USB2 hi speed
hub with its own 5vdc power unit. Can it be that this late
model laptop usb port is a type 1 port instead of type 2???
For such a recently made computer I cant believe that the USB
is type 1. Woner where in "system" can I verify whether its
Type 1 or type 2.
Joe

 

[Barry Watzman]

The manufacturer's specs would tell you if it's a USB 1 or 2 port. Lots
of earlier P4 laptops still had only USB 1.x ports.

Also, you may not have the necessary drivers or OS loaded. Even the
"original" Windows XP did not support USB 2. You need at least service
pack 1 PLUS USB 2.0 drivers for the hardware. There is no official USB
2 support for any version of Windows 9X, but the "Orange Micro" drivers
will work with some of the more common USB 2 controllers.

 

[The Electric Fan Club]

Hi, through Windows XP's device manager, I see I have four 'USB Root
Hub' devices. These correspond to the four usb ports on my laptop, 3
on the right of the machine and one on the left.
When I right click on the devices, and choose 'Properties', I can click
'Power' and for each of the right USB hub devices I'm told there are
'2 ports available'., for the left side one i'm told there are '6 ports
available'

After fiddling though, it seems that two of the actual external usb
sockets on the right of my laptop seem to correspond to one of the usb
hubs - if i put my mouse in one socket, and my bluetooth dongle in the
one next to it, they both show up on the same 'usb root hub' devices'
Power page, and there are no more 'ports' available on this one.

I assume that your machine features the newer USB2 ports. This can cause
much confusion, because examination of the power tabs reveals apparently
more ports than the machine is actually fitted with. You should find that 3
of the root hubs have 2 ports and the remaining one has 6. As you only have
4 physical ports, this suggests that the laptop's chipset is equipped with 6
ports, but only 4 are implemented on your motherboard.

The root hubs with 2 ports are to support the older USB1 standard (OHCI).
When you connect a USB2 device, it is initially connected to the OHCI root
hub at fast speed, and then asked if it is really a USB2 device. If it is,
it is then reconnected to the USB2 root port (EHCI), and Hi speed
communication initiated.

The reason for this duplication is that the method of terminating the bus is
different for the 2 systems. USB2 cannot work with the termination that
USB1 uses.

 

[The Electric Fan Club]

The manufacturer's specs would tell you if it's a USB 1 or 2 port. Lots
of earlier P4 laptops still had only USB 1.x ports.

Also, you may not have the necessary drivers or OS loaded. Even the
"original" Windows XP did not support USB 2. You need at least service
pack 1 PLUS USB 2.0 drivers for the hardware. There is no official USB 2
support for any version of Windows 9X, but the "Orange Micro" drivers will
work with some of the more common USB 2 controllers.

Unfortunately, a few computer manufacturers exploited an ambiguity in the
USB2 spec. A number of computers were sold as having ports complying with
USB2. Unfortunate buyers discovered that 12 Mbps (USB1 speeds) was the
fastest it would work at. The problem was that Issue 2 of the spec.
included the 1.5 and 12 Mbps operation, but neglected to insist that a USB2
port had to include 480 Mbps as well.