60 Hz Line Frequency

[TomL_12953]

In the manual for the Real-Time Clock, it says that unrectified +16v has to be brought to pin 55 of the motherboard to use the RTC with the 60 Hz line frequency. I seem to remember reading here somewhere that this isn't possible with the replicas because of the new power supplies used. I can't find the reference to it now. Does anyone know if this is the case or is my memory faulty? If I can't use the 60 Hz signal, can I use the crystal frequency OK?

TIA

Tom Lake