GitHub - SpenceKonde/megaTinyCore: Arduino core for the tinyAVR 0/1/2-series - Ones's digit 2,4,5,7 (pincount, 8,14,20,24), tens digit 0, 1, or 2 (featureset), preceded by flash in kb. Library maintainers: porting help available!
Technoblogy - Mega Tiny Time Watch [Updated]
problem with GPS module using an attiny 1604 [SOLVED, it was just bad weather] - Networking, Protocols, and Devices - Arduino Forum
Soldered Dasduino LITE (ATTiny1604), 6,40 € - Welectron