Having RTC built in, that's huge for me, been wanting it and always have to add it on... Ya it's just a watch battery type thing (just like most computers)
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But ya, prob most don't need it cause they're connected to networks .. I use PI for boat navigation, tides/currents, etc and I don't always have network so I gotta have RTC Incase I loose power or the tides don't know what time it is 😂