INT 21 - European MS-DOS 4.0 - "PARTITION" - GET/SET FOREGROUND PARTITION SIZE
	AH = 83h
	AL = function
	    00h get size
	    01h set new size
		BX = new size in paragraphs
Return: CF clear if successful
	    BX = current size (function 00h) or old size (function 01h)
	CF set on error
	    AX = error code (01h,07h,0Dh)(see #01680 at AH=59h/BX=0000h)
Desc:	specify or determine how much memory may be allocated by the foreground
	  process
Note:	if the partition size is set to 0000h, no partition management is done
	  and all memory allocation is compatible with DOS 3.2.
	the partition size can be changed regardless of what use is being made
	  of the changed memory; subsequent allocations will follow the
	  partition rules (foreground processes may allocate only foreground
	  memory; background processes allocate background memory first, then
	  foreground memory)
SeeAlso: AH=48h,AH=4Ah