RCA alarm clock - RP3721 - crystal or AC for time?

They used to use crystals to help the timer ics to keep time but since the development of Micropros. all this is built in to one chip. Now they will use a resonator or a small crystal for the timing clock of the micro but nowdays the manufacture uses that clock to keep all in check. If your gaining time you probably are having problems with your ac duty cycle as this also keeps clocks in check.. This would not affect most devices but could be a problem. But of course a defective Micro could also cause this gain in time And probably is?? Now a battery backup is nothing more then a battery in line with the Microproccesors B+ terminal through of course a diode as well as a voltage limiter resistor to take over the B+ when the units ac supply is absent..