Problem whith Keybord and display multiplexed

I dismount on old printers printed circuits which are mounted a display and a keyboard matrix. The problem for me is that the display and keyboard lines are multiplexed by two integrated circuits, 74hct244 and 74HCT174. I don't understand the operation of the arrangement. I join the scheme. If you could give me some explanations on the party circuit and possibly program ideas, I could use mounts on an arduino (Mega) and save a few inputs / outputs.?

thank you very much

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