Function 14h	Controller Internal Diagnostic		     (AT, XT/286)
entry   AH      14h 
return  CF      set on error 
	AH	status code (see Int\13f\01)
note 1) OEM is Western Digital 1003-WA2 hard/floppy combination controller 
	in AT and XT/286. 
     2) Used for diagnostics only in PS/2 systems