pub const PRELUDE_GB: &str = "$C020 constant last-key\n$C022 constant random-register\n$9800 constant graphics\n\n\\ https://www.copetti.org/writings/consoles/game-boy/\n\n20 constant screen-width\n32 constant screen-row-width\n18 constant screen-height\n\n37 constant left\n38 constant up\n39 constant right\n40 constant down\n\n: random random-register @ 255 and swap % ;\n\n0x02 constant TILE_WALL\n\n0x00 constant color-white\n0x02 constant color-black\n0x03 constant color-green\n0x04 constant color-red\n\n: draw-index ( color index -- )\n graphics + c!\n ;\n\n: read-index ( index -- color )\n graphics + c@\n ;\n";