Nixie Tubes Multiplexing and Fading

Example of multiplexing 6 tubes including fading effect, code works for 6 tubes (hours minutes seconds), but there is only 2 nixie tubes to display that. All six tubes [will be] driven by one K155ID1. Anodes controlled via MPS42 MPSA92, resitor (1206) [ in future]. Original code was written in Arduino IDE including low level optimizations (direct port controlling, simplifications in DS1307 library) due low performance of digitalWrite function.