)
Call HugeRealMode Server "Enable A20" function with:
	AL = 00h
Return: AX = error code (see #03787)
Note:	The HugeRealMode Server requires an XMS-driver like HIMEM.SYS loaded
	  before HUGEREAL (for XMS-memory allocation and A20 control). It
	  utilizes some undocumented 386+ features to enable 4G code and data
	  segments (flat memory model) in the CPUs real-mode. It is not
	  compatible with V86-mode (as with most EMM386). For maximum speed
	  and compatibility with DOS it uses a two stage interrupt model
	  (see #03791)
SeeAlso: #03789,#03790,#03791