The present disclosure describes writing information on substrate displays. In an example, a display on a substrate is interfaced. The interfacing includes constraining a first longitudinal side of the substrate via a first actuable slot. Further, a second longitudinal side of the substrate opposite to the first longitudinal side is constrained via a second actuable slot. Thereby the substrate is constrained between the first and second slot with the display positioned therebetween. Further, the display is operated to write information thereon via an imager while the substrate is constrained between the first and second slot.