Int 15 Fn 2303  U - Ibm Bios - Smart Energy System - ???                   [B]

   AX = 2303h
   BX = ??? ('x')
   DX = 'y' and 'z'
       bits 15-7 = 'y'
       bits 6-3 unused
       bits 2-0 = 'z'
   DI = ??? (0352h)

Return: ???

Notes: performs graphics functions, writes to segment A000h and VGA I/O ports
   IBM classifies this function as optional