Int 67 Fn 5E03  - Nanosoft Md386 - Enable/disable Memory Write Protection  [m]

   AX = 5E03h
   BL = register map set number
   BH = new state (00h read-only, else read-write)
   CX = linear page number (linear address SHR 12)

Note:  setting write protection in map set 0 will cause the setting to become
     the default for newly-allocated map sets