Int 21 Fn F9  - Doubledos - Set Timesharing Priority                       [T]

   AH = F9h
   AL = priority
       00h visible program gets 70%, invisible gets 30% (default)
       01h visible program gets 50%, invisible gets 50%
       02h visible program gets 30%, invisible gets 70%
       03h Top program gets 70%, bottom program gets 30%
       04h Top program gets 30%, bottom program gets 70%
       05h get current priority

       Return: AL = priority setting

Note:  identical to AH=E9h

See Also: AH=E9h"DoubleDOS",AH=FAh"DoubleDOS",AH=FBh"DoubleDOS"