INT 13 - Future Domain SCSI CONTROLLER - GET POINTER TO FREE CONTROLLER RAM

	AH = 1Ch
	DL = hard drive ID (any valid SCSI hard disk)
Return: CF set on error
	    AH = status code (see #00234 at AH=01h)
	CF clear if successful
	    ES:BX -> first byte of free RAM on controller
Notes:	the Future Domain TMC-870 contains 1024 bytes of RAM at offsets 1800h
	  to 1BFFh on-board the controller for storing drive information and
	  controller status; ES:BX points to the first byte available for other
	  uses
	ES contains the segment at which the controller resides; the
	  controller's two memory-mapped I/O ports are at offsets 1C00h, 1E00h
SeeAlso: AH=1Bh"SCSI"