XPost: comp.os.ms-windows.misc, alt.comp.os.windows-7, alt.windows7.general   
   From: nospam@needed.invalid   
      
   On Sat, 8/16/2025 1:36 PM, Steve Hayes wrote:   
   > On Sat, 16 Aug 2025 16:24:40 +0100, "J. P. Gilliver"   
   >  wrote:   
   >   
   >> I have had PCs that wouldn't boot if a USB memory stick was plugged in.   
   >> I can't remember whether it was any memory stick in any port, or just   
   >> certain sticks, or certain ports. It would have been, I'm pretty sure,   
   >> either Windows 7 or XP (USB under Windows 9x was pretty flaky anyway). I   
   >> haven't had that problem with this W10-64 machine, but possibly only   
   >> because I've never tried booting it with a stick plugged in so far.   
   >   
   > I have sometimes had the problem if it not booting in those   
   > circumstances. But not always. It only happened about 1 in 10 times.   
   >   
   > The USB had drive has its own power supply, and it now sees neither   
   > that nor any flash drives, nor the printer.   
   >   
   > It still sees they moust and the keyboard (otherwise I wouldn't be   
   > able to type this).   
   >   
   >   
      
      
   I might test the hardware with some other OS, just to see if the   
   symptoms are the same or not. Like a Linux.   
      
   The drivers are OHCI, EHCI, XHCI.   
      
   On WinXP, the XHCI came with my NEC card with the USB3 chip on it.   
   Some brands, like an Asmedia, they didn't come with a WinXP XHCI driver.   
   That's why the NEC was unique, in that a NEC chip was more likely to   
   be perfectly useful on WinXP.   
      
   The OHCI and EHCI came with the OS.   
      
   Maybe the OHCI driver is being used for the keyboard and mouse.   
      
   But why a certain subset of hardware types are not showing up, like   
   a USB with its own power supply, I would have to guess it is a driver   
   issue, but it would be pretty weird if one of the drivers did not   
   load, and it is possible the hardware is supposed to work (to some   
   degree) with either of those.   
      
   On older hardware, a USB2 block and a USB1 block were connected to a   
   mux, and during negotiation, it would be decided just which block   
   should be used. Maybe it would start with one block, then flip over   
   to the second block if the "speed declaration" said that would be OK.   
      
   Whereas on newer hardware, the "thing" facing the peripherals is   
   a hub that does the selecting, and a hub driver loads instead.   
   And this kind of hardware design, causes the max number of hubs   
   in a row, to be reduced by one hub.   
      
   Sorry, nothing else comes to mind so far.   
      
      Paul   
      
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