The datasheet in the archives here for the MCCS1850 Real Time Clock didn't contain any searchable text, so I ran it through some OCR software to convert the images to text. This will come in handy if someone wants to design a replacement with a microcontroller and crystal. Hmmm, that was oddly specific.
The new datasheet can be found here:
https://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Datasheets/MCCS1850.pdf (
https://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Datasheets/MCCS1850.pdf)