more then 64 ssd1306 screens

i use J10 in combination with 74hc595 (latigidon display driver board)

 

it seems to work for 56 screens (+8 from J15)

 

how and where is the multiplexing logic for J10 programmed? and how to expand it to 80 screens? (hi update speed is not needet)

i use customcode based on mios32 - so i could enclude modified lcd functions (no midibox ng…)