INT 21 - Software Carousel - SWITCH TO ANOTHER TASK                             
	AX = DF01h
	BL = task number (00h = next task)
Return: AL = status
	    00h Carousel not running
	    01h successful
	    FFh unsucessful
		AH = error code (01h,02h) (see #01813)


(Table 01813)
Values for Software Carousel error code:
 00h	invalid subfunction in AL
 01h	invalid task number
 02h	tried to switch to task with no memory size
 03h	tried to kill program in partition with no program running
 04h	tried to change size of an active memory partition
 05h	invalid memory size
 06h	tried to send command to task with a pending previous command