up vote 18 down vote favorite
1
share [g+] share [fb]

What does a "Legacy USB Mouse" option in a BIOS mean?

Yes legacy usually means older revision, or obsolete. So legacy usb mouse means support for "old style usb mouses".

That's not really answering the question. As Mr. Tamm, my high school electricity teacher, liked to say, "Yes, and oranges taste orangey."

What does legacy USB mouse support mean?

  • What is a legacy USB mouse?
  • There's an "old style" USB mouse?
  • What changed between what version of usb and what version of usb that made mice incompatible?
  • Why was the change made?
  • When was the change made?
  • Who made the change?
  • What was the virtue of the "new USB mouses" over the "old USB mouses"?

Put it another way:

What is the BIOS doing when "Legacy USB Mouse" option is enabled?
What is the BIOS doing when "Legacy USB Mouse" option is disabled?

See also

link|improve this question
69% accept rate
feedback

2 Answers

up vote 21 down vote accepted

As i understand it, its not the Mouse or Keyboard that's legacy (PS/2 hasn't changed, USB is backward compatable with other USB versions), its the OS - legacy mouse mode emulates a ps/2 or AT device when a USB mouse is used with a OS that dosen't support it.

Not the best source, but this seems to confirm that , as does the last post here

From Platform Compatibility for USB Boot Devices on the Windows Hardware Development Center on MSDN:

Architecture of Legacy Support with Both USB and PS/2 Support

Legacy support is shown in Figure 1 for both USB and PS/2-compatibile support. Important features include:

  • The BIOS traps events from the USB keyboard and mouse and presents them to the system as PS/2-compatible devices.

  • The legacy operating system recognizes the USB keyboard and USB mouse as PS/2-compatible devices, with limitations imposed by the USB boot protocol.

Figure 1. Architecture for Legacy Support for USB and PS/2
enter image description here

link|improve this answer
i'm going to give it to you since you were first, and you explicitly mentioned the idea that legacy mode is where the BIOS will make the USB mouse look like a PS/2 mouse, so that operating systems that only support PS/2 mice (e.g. MS-DOS) will see a PS/2 mouse attached. Once you mentioned that emulation concept, everything clicked for me. – Ian Boyd Jun 28 '11 at 13:28
ooh. nice edit. I didn't know about this till you asked either - looked it up cause i just HAD to know ;) – Journeyman Geek Jun 28 '11 at 13:29
i like to edit people's answers with referenced quotes and pretty screenshots; helps them get more free upvotes :P (although i'm more of a stackoverflow guy) – Ian Boyd Jun 30 '11 at 1:38
feedback
up vote 9 down vote

I found a great explanation:

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.

http://help.wugnet.com/windows/USB-Legacy-BIOS-ftopict606120.html

link|improve this answer
beat you to it ;) that's my first link. – Journeyman Geek Jun 28 '11 at 13:20
@Journeyman Geek Sorry, I had the page open for a while before I typed. I often go through and open all the questions I may be able to answer. I did not refresh before answering, so I did not see your answer. – KCotreau Jun 28 '11 at 13:26
@Journeyman Geek P.S., if it is any consolation, I did upvote your answer. :) – KCotreau Jun 28 '11 at 14:16
feedback

Your Answer

 
or
required, but never shown
discard

Not the answer you're looking for? Browse other questions tagged or ask your own question.