KenK wrote:
Paul wrote in news
KenK wrote:

Nope. Didn't work. System said no keyboard found when booting and
mouse pointer was frozen when system started. sigh I was hoping...
OK, next question. Do any of these
subsystems (PS/2 or USB) light up any LEDs ?

The external HD has an LED ndicator that works

You can use BIOS settings, to completely
disable the USB subsystem (from functioning,
not from lighting the LED necessarily).

In the USB2 era, there was a separate page in the BIOS
screen, with all sorts of stuff for USB. Including
the ability to turn stuff off.

In cases where you've hopelessly damaged the BIOS
settings, you can use the Clear_CMOS jumper to start
over again. You do that with the power cable pulled
from the computer (as the Clear_CMOS jumper can burn
a little ORing diode if you leave the computer powered).

But beware. On some computers that you find in the junk pile,
the internal graphics are damaged. If you reset the
BIOS on these older computers, they default to selecting
the internal graphics, and they won't use the video card
right away. And you have to be able to see the screen,
to set the BIOS to using the add-in video card. Machines
with internal graphics which are non-operational, then you
cannot afford to reset the BIOS. If you use the
Clear_CMOS jumper on such machines, you end up
locked out. You have to know a bit about the equipment
you're working on, to have some idea whether this
is a possible outcome. The two machines I use in the
room today here, don't have this as a possible outcome,
and I should always be able to recover them.

That makes it possible to pretty well completely lock yourself
out of the computer. You have to be born unlucky for
that to happen, but it has happened to posters visiting
USENET.

If you can get some sort of keyboard working, even if
it's PS/2, you can take a look in the BIOS settings.
And see if something was turned off by accident.

On motherboards with USB1.1 ports from the Southbridge,
and USB2 ports from a NEC add-on USB chip, the NEC ports
don't work right away at BIOS level. And you use the
USB1.1 ports for the keyboard, if you expect to use
the USB keyboard in the BIOS. However, the keyboard
will work on the NEC chip, once the OS boots. Maybe you
might see this on a year 2005 computer or so.

The Southbridge USB ports, generally always have full
support at BIOS level. Add-on chips outside of that,
don't have code modules to help them at BIOS level.
However, I think my newest machine, it does boot
from a NEC USB3 chip which sits outside the Southbridge.
But the older computers, like year 2005, the support
was much poorer back then.

Once the OS comes up, they should all work.

WinXP has USB2 drivers at least. For USB3 add-on cards,
you'd need to use the driver disc, to have the OS
recognize the ports. Windows 7 suffers the same fate.
Windows 8 and Windows 10 have USB3 drivers in-box.

Paul