uRTC-8 is a universal RTC that can be connected via a [[UIDE_Universal_IDE_adapter_cards_for_Z-80_computers#Z80_Shims|Z80 Shim]] to any Z80 computer that has a socketed CPU. It is also compatible with the [[UIDE_Universal_IDE_adapter_cards_for_Z-80_computers#Machine-specific_expansion_port_adapters|uIDE-8 PcW expansion port adapters]]. Both of these connectivity options present a 40 way "Z80 Bus" and you can connect uRTC-8 to this bus, in parallel with other devices on the bus.
uRTC-8 uses an 8 bit comparator and a set of jumpers to enable I/O base address selection, just like uIDE-8. The RTC used is an Epson RTC72421 which has 16 registers, directly accessible via IN and OUT instructions. As a result, the base I/O address is a four bit number between 0000 and 1111 (0-15), putting the device at any of the I/O addresses 00h, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, A0h, B0h, C0h, D0h, E0h or F0h. From any of these base addresses to [base address + 0Fh] are the 16 registers of the Epson RTC. The default base address is 80h, and this is what uRTC.COM expects. Contact me if you need to set a different I/O base address.
uRTC-8 is powered by the host computer, but also has a battery backed supply to maintain the time and date when the host is powered down. The battery is a common CR2032 3v button cell.