CIS-4

I have ported the code to ATTiny85.  To make a long story short, the first version 

hat could fit the Digispark used 99% of flash 

The second version calling functions that dealt with PROGMEM and using tiny versions for RTC, neopixel and I2C (wire) libraris still took me 95% of the flash.

I have then replaced the Wire and RTC libraries with my own code and now the sketch takes 87% of the flash. 

There's still some room for improvements, but that's good enough! for the moment.

Sources available at project's Github repository

This video shows the flip mode.

When in Cistercian mode, a short press on the button will display the time in decimal mode (flip)