From: muta...@gmail.com   
      
   Currently I read the FAT boot sector which contains,   
   among other things, the number of heads and the   
   number of sectors per track.   
      
   I use those values in the boot sector code to convert   
   an LBA into CHS.   
      
   Someone has reported the "University Challenge" disk,   
   which is only 40 MB instead of the normal 1 GB, not   
   working on Hyper V under Windows 11.   
      
   The UC disk works fine on real hardware and qemu   
   and Bochs.   
      
   I haven't proven 100% but it is certainly getting to the   
   boot sector and I think it has an issue in there, not   
   loading the 3 sectors of the boot loader properly.   
      
   I suspect the problem is that the 40 MB drive uses   
   some "real" disk geometry values instead of the   
   fake ones needed for large disks.   
      
   Hunting around I found INT 13H AH=08H which looks   
   like it will retrieve the number of heads and sectors   
   per track actually being used by the BIOS, and I would   
   have thought that was the definitive values, which   
   should overwrite the values stored in the BPB of the   
   boot sector.   
      
   Is that the right approach?   
      
   Thanks. Paul.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)