INT 15 - later PSIBM PS/2, any model/2s - ALLOCATE DMAsee Direct Memory Access ARBITRATION LEVEL
	AH = CEh
	BL = 00h-0Eh arbitration level to be allocated
	     0Fh-FFh reserved
	AL = option byte
	    bit 7-1: reserved (0)
	    bit 0: 0 = need DMAsee Direct Memory Access channel for arbitration level requested
		   1 = no channel required for arbitration level
Return: CF set on error
	    AH = status (80h,86h = function not supported)
	CF clear on success
	    AL = channel number
		00h-07h channel number allocated for the arbiration level
		08h-FEh reserved
		FFh	no channel requested for arbitration level
	    AH = status (see #00531)
Notes:	 arbitration level 00h has the highest priority, 0Eh the lowest
	 to perform a DMAsee Direct Memory Access transfer operation, be sure to call this function
	   first, and call AH=CFh afterward.  Failure to use this function
	   can cause unpredictable results.
SeeAlso: AH=CFh


(Table 00531)
Values for DMAsee Direct Memory Access arbitration status:
 00h	success
 01h	arbitration level not available
 02h	channel not available
 03h	invalid arbitration level passed