Int 15 Fn 4900  - Far East MS-dos - Get DOS Type                           [D]

   AX = 4900h

Return: CF clear if successful
       AH = 00h
       BL = type of DOS running
       00h DOS/V
       01h DOS/J or DOS/K (early IBM Japan versions of MS-DOS)
   CF set on error
       AH = 86h (function not supported)

Note:  in practice, DOS/J returns AH=86h; AX DOS does not support this call

See Also: INT 21/AH=30h