Int 21 Fn 2508  P - Phar Lap 386/dos-extender - Get Segment Linear Base A  [E]

   AX = 2508h
   BX = segment selector

Return: CF clear if successful
       ECX = linear base address of segment
   CF set if invalid segment selector

Note:  this function is also supported by FlashTek X-32VM

See Also: AX=2509h