Solving Usb Problems - Compaq Armada M700 Series Reference Manual

Problem
External device
connected to a
USB connector
does not work.
External device
connected to
USB connector
does not work
during startup
(before
Windows 95 or
Windows 98
loads).
External
devices in
lower tiers do
not work.
13-20 Troubleshooting

Solving USB Problems

Possible Cause
The operating system
limits external devices
connected by USB to two
tiers which can include
no more than two hubs
on the first tier and no
more than one keyboard
and one pointing device
on the first or second
tier.
During startup, only two
tiers are supported by
the USB port. These tiers
can include no more than
two hubs on the first tier
and no more than one
keyboard and one
pointing device on the
first or second tier.
An unpowered hub is
connected to another
unpowered hub.
Solution
Reduce the number of
connected external USB
devices to no more than
two hubs on the first tier,
and no more than one
keyboard and one
pointing device on the
first or second tier.
Use the external device
only after Windows 95 or
Windows 98 has loaded.
Reduce the number of
connected external USB
devices to no more than
two hubs on the first tier,
and no more than one
keyboard and one
pointing device on the
first or second tier.
Use only powered hubs.
Make sure that all
unpowered hubs are
immediately preceded by
powered hubs in the
USB chain.