What is "legacy" USB in motherboard BIOSes?

[tashirosgt]

I have several models of motherboards who BIOSes have settings related to "legacy" USB. The settings may mention "legacy USB mouse" or "legacy USB storage" or "legacy USB function". The default is invariabley "enabled". The motherboard manuals don't explain what "legacy" means in this context. What is it?

[Dan]

This may help.

http://www.overclockers.com/forums/s...d.php?t=242655

[tashirosgt]

Originally Posted by Dan

This may help.

http://www.overclockers.com/forums/s...d.php?t=242655

Ah...what? The post that talks about HP support for USB sounds authoritative and irrelevant to motherboard BIOSes. The thought that "legacy USB" means USB 1.1 (or USB 2.0 now that there's a 3.0) is interesting, but I'd think that these standards would provide for backward compatibility. Can you disable support for 1.1 and still say your support USB 2.0?

[Dan]

From post number 6 on that page:

"Legacy USB support provides USB functionality in environments where there normally is not USB support. Specifically, HP provides legacy USB functionality at:

* Power On Self Test (POST)
* ROM-Based Setup Utility (RBSU)
* Diagnostics
* Environments which do not support USB natively

USB devices support hot-plug at the OS level. USB devices also support hot-plugging the devices in legacy USB mode, but this feature requires additional ROM support. The table below shows what minimum ROM version is required for hot-plug functionality of USB devices in legacy mode. Servers that support legacy USB are enabled by default. To disable legacy USB support, complete USB functionality must be disabled by disabling the USB Host Controller in RBSU under PCI Devices.

Legacy USB support requires a system ROM that includes this functionality. All servers shipping in 2003 will have full USB support, meaning they will support keyboard, mouse, floppy, CD-ROM, and will support hot-plugging floppy and CD in legacy mode unless noted differently in the table below. The following table shows the minimum required ROM version to support legacy USB devices."

from:
http://h18004.www1.hp.com/products/s...b-support.html

[tashirosgt]

Originally Posted by Dan

From post number 6 on that page:

"Legacy USB support provides USB functionality in environments where there normally is not USB support."

But how do motherboards with USB ports make sense as "environments where there normally is not USB support"?

Originally Posted by tashirosgt

But how do motherboards with USB ports make sense as "environments where there normally is not USB support"?

Try this

http://www.usb.org/developers/devclass_docs/usb_le9.pdf