POV-Ray : Newsgroups : povray.off-topic : USB Hardware riddle : Re: USB Hardware riddle Server Time
10 Oct 2024 19:22:38 EDT (-0400)
  Re: USB Hardware riddle  
From: Darren New
Date: 7 Mar 2008 14:37:13
Message: <47d19969$1@news.povray.org>
Tim Nikias wrote:
> Any ideas? Is there a USB Hub Priority or some such idiotic "feature"?

No. The problem is that each USB device is supposed to have a unique 
serial number, so the OS knows when you plug the same device into a 
different port. On a sufficiently cheap piece of USB hardware (espcially 
those where it doesn't matter, like a mouse), they don't manufacture the 
bits that are different for each item.

Hence, when you plug the same device into the same port, Windows says "I 
saw that before, but it doesn't have a serial number, so I'll assume 
it's the same thing." When you plug it into a different port, Windows 
assumes it's a different device, and goes through the install dance again.

Same thing happens if you wipe out the serial number on the drive inside 
a USB disk enclosure - Windows doesn't know it's the same disk, and 
reinstalls it.

(Reading the USB specs, and how you're supposed to handle such things, 
is actually the correct way of figuring this out, rather than guessing. ;-)

-- 
   Darren New / San Diego, CA, USA (PST)
     "That's pretty. Where's that?"
          "It's the Age of Channelwood."
     "We should go there on vacation some time."


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