Int 21 Fn 252C  P - Phar Lap 386/dos-ext Vmm V3.0 - Add Unmapped Pages At  [E]

   AX = 252Ch
   BX = segment selector
   ECX = number of 4K pages to add

Return: CF clear if successful
       EAX = offset in segment of beginning of unmapped pages
   CF set on error
       EAX = error code
       08h insufficent memory
       09h invalid selector
       82h not supported by current DPMI