INT 2F - MDEBUG display driver - SHOW SAVED DATA                                
	AX = D004h
Return: CF set on error
	CF clear if successful
	    display switched to mode it was in before calling AX=D002h and the
	      display memory is restored
Note:	This function needn't save the display memory before changing it.
SeeAlso: AX=D000h,AX=D005h