By “playing” with some unofficial (but documented) settings for the TMS9918A I was able to get a special graphics mode that I renamed “extended graphics 2” (ExG2). In this mode, the VDP addresses the pattern table like in graphics 1 mode while keeping the color management of the graphics 2 mode. So, we have only 256 patterns like in G1 but, unlike in G2, they can be repeated in any of the video cell. Unlike in G1 mode, where the color is set for groups of 8 patterns, in ExG2 mode we can set a color of every byte of the pattern, so that we can have 2 different colors for each row of 8 pixels or, like in the picture, set the same main and back colors for the whole 8×8 pattern. PS: I’m still not sure if everything is working well… just doing some tests.
TMS9918 – special video mode
