USB Legacy in BIOS

[attilathehun1]

I'm having some problems with my PC. I went into BIOS and one of the options
is to enable, disable USB Legacy. What is the purpose of USB Legacy? Also
what will the result be if I leave it disabled?
Any help would be greatly appreciated!
Thanks, attilathehun1

 

[Colin Barnhorst]

Google on "usb legacy" and you will find a lot of info.

 

[Karl Snooks]

Attila the Hun 1,
For XP computers, disable USB legacy support in your bios.

What is legacy support?
In USB terms, this is USB device support built into, or specific to, a
particular computer system. Legacy mode support is inherent to a system and
is typically provided by legacy hardware interface emulation.
Legacy mode support allows devices to function in an operating environment
that is not USB-aware. For example, legacy mode support for a USB keyboard
and mouse resides in the system BIOS and presents the keyboard and mouse
data via the port 60h/64h/IRQ1/IRQ12 interface.
Source: USB PC Legacy Compatibility Specification

The preceeding was copied from the Platform Compatibility for USB Boot
Devices site listed below:

Platform Compatibility for USB Bood Devices
http://www.microsoft.com/whdc/archive/usbcompat.mspx

Search Results for bios usb legacy support XP
http://search.microsoft.com/results...0=Search&FORM=QBME1&l=1&mkt=en-US&PageType=99


Universal Serial Bus - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Universal_Serial_Bus

USB.org - USB FAQ
http://www.usb.org/developers/usbfaq/#cab1

Universal Serial Bus Devices Do Not Work in Safe Mode
http://support.microsoft.com/kb/310496

The computer stops responding during startup
http://support.microsoft.com/kb/832577

karl snooks

 

[Opinicus]

I'm having some problems with my PC. I went into BIOS and one of the
options
is to enable, disable USB Legacy. What is the purpose of USB Legacy? Also
what will the result be if I leave it disabled?
Any help would be greatly appreciated!

If your (only) keyboard and mouse are attached to your PC by a USB
connection (as mine are) and USB legacy is disabled, then when you start up
your computer you won't have a keyboard or a mouse.

 

[Lil' Dave]

In a nutshell, legacy is a reroute of USB keyboard and/or mouse to allow an
OS to use same. XP does not need legacy support of a USB keyboard or mouse.

An example of where legacy support is required of a USB keyboard is real
mode msdos. And, a USB mouse would be addressed as a standard PS/2 mouse in
msdos using its mouse driver with legacy support enabled.

 

[Opinicus]

In a nutshell, legacy is a reroute of USB keyboard and/or mouse to allow
an OS to use same. XP does not need legacy support of a USB keyboard or
mouse.

I didn't know that...

 

[Bill in Co.]

So it would be best to leave that option on, in case you ever wanted it, for
such cases? Is there any drawback to leaving that legacy enabled?

 

[Lil' Dave]

Sometimes the legacy thing is a problem for the keyboard on some older
motherboards. I leave the bios set to stop on any fault (default). These
motherboards I'm talking about can't find a USB keyboard with legacy
disabled. And, you can't get to the bios to change it as the bios can't
find a keyboard. All the ones I've found like this also had a PS/2 port for
a keyboard. So, in this case, you might as well stick with a PS/2 keyboard.

XP seems to know what to do with legacy and USB, and uses the USB
communication version hardware. Motherboard mounted that is.

 

[Bill in Co.]

I'm not sure I understand what you said.

It sure sounds like leaving Legacy enabled would cover ALL bases, and if
that's the case, I wonder why there's even an option to disable the Legacy?
Hmmm, but that sounds too simplistic.

So I guess one might "assume" that it's normally preferable not to select it
(Legacy), unless you know you are going to need it - for reasons that are
still unclear.

 

[R. McCarty]

Legacy USB can cause issues with some peripherals. Years ago I had
a Maxtor One-Touch USB drive. If I enabled Legacy USB in BIOS &
the Maxtor was powered on, it would hang on Boot as it tried to do a
mount on the pre-GUI XP phase of booting. Doubtful today that you'll
encounter those type of issues but they can happen.