INT 67 - Nanosoft MD386 - GET ALTERNATE MAP STRUCTURE                           
	AX = 5D04h
	BX = alternate register set number
	ES:DI -> 1024-byte buffer for map structure
Return: AH = status (see #03648)
	buffer filled if AH=00h
Note:	used for debugging purposes
SeeAlso: AX=5D05h