Reminds me somewhat of Teletext graphics, whose character set included 2x3-cell blocks that could be displayed either joined up or separated.
...On a side note, I think you kickstarted me down the path of abstracting the drawing algorithms and implicit matrix protocol out, just to make it easier to implement this with different character sets. One set for example could be [U+2596 .. U+259F, U+2589], so basically just a 2x2 grid per character.