INT 21 - DoubleDOS - SET TIMESHARING PRIORITY                                   
	AH = E9h
	AL = new priority (see #02089)
Return: AL = priority setting if AL=05h on entry
Note:	identical to AH=F9h
SeeAlso: AH=EAh"DoubleDOS",AH=EBh"DoubleDOS",AH=F9h"DoubleDOS"


(Table 02089)
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