O.k., in this case, could you maybe please explain me something?
With all the known revisions the chips have another letter. There is sf2ua, b, c, d, e, f, g, i, k. (The letters always match the letters on specific chips.)
Until now there have never been two boards with a different revision date, but the same letter.
So, if you really think that there is an arbitrary number of "Street Fighter II" revisions, what do you think would be the letter on the chips of a board that came out between version d and version e?
Isn't it a strange coincidence that the known revisions just happen to have a separate letter each time? If there is really an unknown number of undumped versions, shouldn't there statistically be at least two versions where the letter is the same while the revision date is different? Don't you think it's a bit too much of a coincidence that in the moment, the boards that are known, also all have distinct letters?
So, really, what would you imagine a board with a date that lies between sf2ud and sf2ue to look like? Would this have chip names like "sf2u 30d1/2"? Or "sf2u 30d.5"? Or "sf2u 30 de" Not really, right?
As far as I see it, every new revision has a new chip letter. There are no two regular board versions with a different in-game date, but the same letter on the chip labels.
As a consequence, you always know how many revisions are missing: In the moment, all that could appear from somewhere is the H version and the J version (not to be confused with the Japanese versions). And anything that might be beyond K.
But the possibility that in the next few years you might find, like, five new boards that all lie between the currently oldest and currently newest revision, that's basically impossible. Because what letters would these revisons have? If you say "The same letters as the current games", then you need to tell me why you think that there can be two revisions with the same letter, but a different date, even though this has never happened with this game until now. Until now, chip letter = revision distinction. For each chip letter there's exactly one revision date number. If you think another constellation is possible, please show me at least two boards taken from regular arcade machines where the revision date is different, but the chip name is the same, to back it up that this is even possible.
Which brings me back to that strange version 910204: The fact that this board has the same revision letter as the version 910206 even though this never happened with any other version (which statistically it should have, as I said, if there are really 30 versions of the game out there that all share 11 letters), and the fact that the letter A is written in a very strange way with a much thicker font than the rest of the chip label texts, leads me to one conclusion: This is either some custom hack of sf2ub (910214) with the letter B overwritten manually with a marker and that's why the letters look so different. (I need to see a better picture of the board to see if that's true.) Or this is really a rare prototype that was never used in a real arcade.
The theory that this might be just some regular currently undumped version that exists in 100 arcades all throughout the USA, that's pretty unlikely since, as I said, until now it has never been witnessed that two versions of the game with different revision dates share the same letter.
What do you say about this?