INT 1F - NEC PC-9801 - COPY EXTENDED MEMORY                                     
	AH = 90h
	ES:BX -> global descriptor table (see #00499 at INT 15/AH=87h)
	CX = number of bytes to copy
	SI = 0000h
	DI = 0000h
Return: CF clear if successful
	CF set on error
	???
SeeAlso: INT 15/AH=87h