On the older 737 (300/400/500) EHSI, there is a single display mode for VOR and ILS display, whereas on the New Generation models (600/700/800/900), there are two distinct modes (VOR / APP).
I cannot find any reasons for that exept that the weather does not seem to be displayed on the APP mode of the New Generation EHSI, making it easier to read. Is it a possible reasons (ILS display not "disturbed" by weather informations) and are there other reasons for that evolution ? (that seem to make things a bit more complicated, having two modes instead of one).
Thanks in advance for your input,