slot's screen shaders are ports of shaders from the libretro shader collection
https://github.com/libretro/glsl-shaders

LCD3x by Gigaherz. Public domain.

Dot by Themaister. Public domain.
Changes: sharper dots (falloff 4.0) and a 0.85 blend.

zfast_lcd_standard by Greg Hogan (SoltanGris42), copyright (C) 2017.
GNU General Public License version 2 or later.

simpletex_lcd by jdgleaver, using the line weighting of zfast_lcd_standard.
GNU General Public License version 2 or later.
The paper texture (assets/paper.png, a 1024x1024 crop of textured_paper.png) is from the same shader.
Changes: the grid bias is 1.0, so black pixels carry no grid.

slot itself is GNU General Public License version 3 or later, which these licenses permit.
