It supports the F18A for reduced flicker
The Ti's bitmap mode has two separate tables - one for the pixels, and one for the colors. By necessity, they are updated separately, but the TI is too slow to update them both in a single frame (in frame, it takes about 6 video frames). This means that you can watch it paint, and you can see when the pixels change, then the colors. To reduce that effect, I paint the video in four chunks, so that the pattern and color writes are closer together. But it still takes more than a frame, meaning you get a sort of a 'sparkling' or 'twinkling' effect when the raster happens to catch an in-between state.
With the F18A, I take advantage of the high-speed GPU and extra RAM to mitigate that to almost zero. The CPU first writes the pattern to an offscreen buffer, so it doesn't affect the display. The GPU then quickly moves the data to its own private memory, and the CPU simultaneously uploads the color data. When it's done, the GPU can use its high speed plus direct VRAM access to quickly write the pattern and color bytes one after the other. The twinkle is still possible if the raster catches the exact right moment, but it's very, very, very rare.
The good news is that since releasing the demo I solved a problem that had been baffling me related to the flicker, and now the raw 9918A version is also substantially improved. I'll hopefully get a hardware video out this weekend to show it. I have a standalone filter that can reduce the changes to the pattern table between frames, which greatly reduces the twinkle -- the program reports changing 45% of the pixels for the better on Dragon's Lair. (And this is not a lossy change, the end result is the same). I'll update my video conversion tools to include this filter soon, too, and I updated all my sample converted videos.