...
  Is XP
guaranteed to map 0x000c0000 physical  into c000:0  
 virtual in a
 VM86 session?  Does it keep the whole ROM space
mapped to  
 its corresponding
 physical addresses?  It certainly has to hide the
video  
 RAM...   I would
 have expected it to replace the ROM with one of
its own as well. 
 I don't believe XP does anything more than copy the ROM into
 a bank of RAM and then map the RAM.   
 
On Pentium systems, at least the current ones, a larger "page" is used to
map most of the kernel memory into every logical address space with a single
entry. IIRC the default mapping is 4 MB.
Gil