INT 67,4E - Get/Set Page Map Context (LIM EMS 3.2+)

	AH = 4Eh
	AL = 00  get page mapping context into array
		 ES:DI = pointer to destination array
	     01  set page mapping context from array
		 DS:SI = pointer to context source array
	     02  get and set page mapping registers at once
		 ES:DI = pointer to destination array
		 DS:SI = pointer to context source array
	     03  get size of page mapping array
	     04-31  reserved


	on return:
	AH = 00  success
	   = error code (see EMS STATUS)
	AL = bytes in pagemapping array (when AL=3)
	ES:DI = pointer to array with mapping info (AL=00/02)

	- an error will occur if ES:DI points to a buffer that will
	  cause a segment swap
	- designed for use by multitasking operating systems only