Int 67 Fn 5DE7  - Rm386 - Set Page Table Bits For Range Of Pages           [m]

   AX = 5DE7h
   BL = page table bits to be set (bits 2-0 = U/S, R/W, P)
   CX = number of pages to set
   DX = first page number to set (in first megabyte)

Return: AH = status
       00h successful
       8Bh invalid destination page (not in first megabyte)
       A5h invalid page bits
       A6h invalid page count (overflows first megabyte)

Note:  RM386 traps this functions on the initial transition to protected
     mode caused by the INT instruction, which means it can not be
     overridden simply by hooking the interrupt