Folks, do you realize how ridiculous this is ? "be a bit more friendly instead" , " don't steal mrbombermillzy thread" , "telling us not to bother with them" ... I did not know that forum is place where opening some thread is like performing some show. And that OP should have some special rights.
I never said that not to bother. I explained what I consider video mode. Not to mention that saying to someone that is wrong has nothing with being friendly. There is so much things mixed up here, in technique and in human relations.
And I think that I will just say some arguments more (that would be what people should do more in discussions), and move away from this thread. Maybe if I would have TT, could be more interested and even contribute, but no TT, and actually no time too to go deeper in this.
So, we have repeated words as "reserved" and "unused" video modes here. This is what bothered me from first moment. According to OP, every bit combination in video mode register should have some valid mode. And that's the crucial word: valid. In literature often they just say that it is invalid, and results are unpredictable. For instance in opcodes of some CPU. There are 2 bits for setting video mode of ST(E), so we must have 4 video modes ? No, designers did 3 video modes, and period. Now, I''m not saying that invalid combination may not result in something, but that is just not reserved mode, and especially not unused. It would be reserved if designers planned some 4th video mode for ST. But there is nothing about it as I know.
Actually, Atari ST line design is not known about well thought reservations (to say so).
1st example: location of TOS ROM - they provided only 192 KB space for ROM in ST design - 4 years later they were forced to move ROM start to different, lower address, so 256 KB ROM can fit. Fortunately, they moved it down much more, so was no more moving in case of TT and Falcon. You always can learn something ...
Even 'better' case is:
2nd example: ST has 512 colors, and that means 9 bits, 3-3-3 bits for each basic color. What means that need 2 bytes. And they defined bit layout so, that bits 0-2 in each of first 3 nibbles are used, what is good, of course. Until design of STE with 4096 colors, so 12 bits for . And they solved adding 1 new bit for each basic color (RGB) so, to maintain compatibility in max possible extent. But bit order is just wrong - bit 3 is actually less significant, while it should be bit 0, of course. This is certain indicator that there was no any reserve made in ST shifter for future expansions.
Furthermore, whole design of ST video stage is done with not slowing CPU by video stage in mind. Adding some new mode with more res, more colors at once on screen would need complete new shifter design, and more: new MMU too.
Well, good luck in exploring TT's video stage. It may be that you really find something usable. But I will never call it 'reserved' mode. I guess that who did not get so far why, will never get it
Negative feedback has usually positive effect.