INT 67,40 - Get EMM Status (LIM EMS 3.0+)

	AH = 40h

	on return:
	AH = status

	     00  success
	     80  internal software error
	     81  hardware malfunction
	     83  unallocated or invalid handle
	     84  undefined function requested
	     85  no handles available
	     86  error in save or restore of mapping context
	     87  more pages requested than physically exist
	     88  more pages requested than currently available
	     89  zero pages requested
	     8A  invalid logical page number
	     8B  illegal physical page number
	     8C  context stack out of memory
	     8D  context save failed, handle already has context stack
	     8E  context restore failed, no context stack for handle
	     8F  invalid subfunction
	     90  undefined attribute type
	     91  feature not supported
	     92  success, portion of the source region was overwritten
	     93  length of source or destination region exceeds length of
		 region allocated to either source or destination handle
	     94  conventional and expanded memory regions overlap
	     95  offset within logical page exceeds size of logical page
	     96  region length exceeds 1M
	     97  source and destination regions have same handle and overlap
	     98  memory source or destination type undefined
	     9A  specified DMA register set not supported ???
		 specified alternate map register set not supported
	     9B  all DMA register sets currently allocated ???
		 all alternate map register sets currently allocated
	     9C  alternate DMA sets not supported ???
		 alternate map register sets not supported
	     9D  undefined or unallocated DMA register set ???
		 undefined or unallocated alternate map register set
	     9E  dedicated DMA channels not supported
	     9F  specified dedicated DMA channel not supported
	     A1  duplicate handle name
	     A2  attempted to wrap around 1Mb conventional address space
	     A3  contents of partial page map corrupted or count of
		 mappable segments exceeds total mappable segments
	     A4  operating system denied access

	- registers not listed are preserved
	- should only be used after establishing that the EMS driver
	  is present