)
Values for DoubleDOS timesharing 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