I think I have an idea how this mode could be done. It's not entirely flicker free and you would only get 81 colors on screen (9 lumas x 9 chromas). I wonder if this was the method they used ...
You need to set a low res Graphics 7 mode. You will be using two display lists. The first one is a normal Graphics 7 display list. The second, uses a whole bunch of LMS trickery, so that the positions of every group of 2 scanlines are swapped with each other. So while the first screen's display list memory would go like this (using scan line numbers):
0 - 1 - 2 - ...... 94 - 95
The second display list, using LMS trickery, would need to have the screen lines ordered like this:
1 - 0 - 3 - 2 - 5 - 4 - 7 - 6 .... 95 - 94
So basically you are swapping every two scanlines with each other in the second DL.
Now for the real tricky part. You have to stripe the screen between modes 9 and 11, in a method similar to APAC.
Then, you have to swap between the two display lists every vblank, and simultaneously alter the striping each vblank as well. On even frames, the screen will go 11-9-11-9, while on odd frames the screen goes 9-11-9-11.
In theory, this should get you 80x48 resolution (what the above screen appears to be) at 81 colors. It's not entirely flicker free, but would be marginally easier on the eyes than full frame flicker.
The reason for the lowered color resolution is, that when you engage the GTIA modes in graphics 7, you only get 9 chromas or lumas.
I counted the lumas and chromas in the above picture, and can only detect (to my eyes anyway) 9 luma level and 9 chroma level, so it's possible the above screen was produced using a variation of this method. The chromas in Graphics 7.11 run in these colors: 0 (black), 1 (gold), 2 (orange), 4 (red), 5 (purple), 6 (indigo), 8 (blue), 9 (gray-blue), 10 (blue-green). These appear to be the chromas used in the title picture above, so I think it's highly likely this is the method used in this example.
If this was indeed the method used to do this picture, there are other variations possible too:
Doing a 9-10 switch instead of a 9-11 switch will give you a 159 pixel (HIP mode) horizontal resolution, while lowering your colors to 63 (9 luma x 7 chroma), or about 16-20 grayscale if you use monochrome settings, and would flicker less. One could also do a CIN type mode (GTIA normal-11) to get 36 colors (4 luma x 9 chroma) at 160x48. Or by doing a PCIN-type setting (GTIA normal-10) you get maybe about 20 colors, but a lot less flicker since 4 of the color registers are shared on both screens.
There is also the possibility of using what I call Super 9 (or Double-9) mode. The entire screen stays in GTIA 9 but you are altering the COLBK register (background color) instead of the GTIA register. The two colors used would ideally be colors on opposite sides of the color wheel (red-cyan, blue-yellow, or green-magenta) and should get you a duo-shade 81-color screen but with less flicker than the APAC style setting I described above.
It's also VERY possible to use this in a game, as basically you would only need memory for a Graphics 7 screen to make this work.
Edited by Synthpopalooza, Fri May 23, 2014 9:57 PM.