Thanks so much for your answers.
The idea it's to use one Atmega for the screen and control panel interface (input buttons) and another ATmega for the motors and internal machine I/O.
So with the two ATmega I want to create a NC control system for machines.
And NC control it's like a CNC but closed, you don't have the ability to send G code outside, it is all pre-programmed.
I was looking also at the matrix LED displays, but even it can show a lot of text, the screen is too small.