Int 21 Fn 250A  P - Phar Lap 386/dos-extender - Map Physical Memory At En  [E]

   AX = 250Ah
   ES = segment selector in the Local Descriptor Table (LDT) of segment
        to modify
   EBX = physical base address of memory to map (multiple of 4K)
   ECX = number of physical 4K pages to map

Return: CF clear if successful
       EAX = 32-bit offset in segment of mapped memory
   CF set on error
       EAX = error code
       08h insufficient memory to create page tables
       09h invalid segment selector

See Also: INT 31/AX=0800h