Here's a bit of deductive speculation:
When the frontal CAD image was released, as well as the back interior rendering, I was struck by the apparent size and need for a "moire step motor" which took up such a large area of the interior of the Tricorder.
A similar moire on TWC Communicator doesn't need even CLOSE to that much room. So why the change to something *much* more bulky? A couple potential reasons came to mind, so I didn't give it too much thought. But, after Update #3 - specifically this picture:
a new idea came to mind.
This rendering shows the data discs, with some of them 'ejected' from the Tricorder disc "library". When I first saw it, something immediately jumped out at me about the design of these discs. We've never seen these discs removed from the Tricorder. As such, we don't know what they actually look like. But what we HAVE seen of the design has always seemed to suggest just a smooth, shiny undetailed metal disc (much like the smooth rectangular undetailed 'memory tapes' used on the ship itself). Yet TWC has apparently chosen to design the data discs with a large depression of some sort rather than just smooth discs. Why?
Moreover, the shape of these discs looks unaccountably like the shape of the moire circle built into the Tricorder, which is shown in that same image looking uncannily like one of the memory discs.
That makes me wonder - IS the moire circle built into the Tricorder? What if IT is not just a seemingly random design, but is actually one of the discs on a recessed 'reader'? What if the moire effect is a disc's data BEING accessed?
This isn't such a far fetched idea. After all, how exactly are the data discs used on a tricorder? We've always seen how they are apparently *stored*, but we've never seen them removed, let alone used. And there is no apparent mechanism on the Tricorder for the data to be 'accessed'.
Now, it may be the case that data is 'accessed' simply by putting them in the 'storage' rack. That was certainly my initial thought, especially when seeing reference to a "Data disc detection PCB" on the back interior rendering. But that doesn't explain the data disc's similar design to the 'moire' disc.
And, interestingly enough, in their Update # 2, TWC provided a link to what they identify as a 'nice summary' of the history of the tricorder props. One of the images on that site shows the original design of the Tricorder by its creator Wah:
You'll note his drawing is very close to the final design. And, you'll also note that there is a 'reader' for the data discs built into the Tricorder. So the data discs *were* designed to be accessed by a 'reader' on the Tricorder. And, it should be further noted, the Wah data disc even has the same recessed design as the TWC data discs AND the 'moire' disc on the final product, suggesting a relationship between them.
So I wonder if TWC didn't do some cool imagineering for the Tricorder. Perhaps ALL the data discs have a 'moire' built into them, with the separate stepper motor to run it when placed into a recessed circular 'access port' on the front of the Tricorder? That would certainly explain greater amount of space devoted to the 'moire motor'. The data disc could be held held in place magnetically(?), and could be swapped with other data discs with the same 'moire' center built into them.
Additionally, the fact that 'moire' disc seems to have the SAME slot design in *its* center (for a spindle to fit in it and rotate it, which is how the 'moire' is apparently run) as *all* the data discs also seem to have:
This suggests the possibility that the 'moire' disc is a data disc - that you pop out one data disc from that spot and pop in another and it is 'read' by the Tricorder.
(One wonders the purpose of those center circles on the data discs if they are not for the step motor spindle)
Who knows - TWC might even make different style centers to the data discs, to match the differences between the 'moire' discs and the other non-'moire' prism-style 'discs' which were shown on different Tricorders in TOS (something also noted on the same 'good summary' site recommended by TWC):
As I said, all of this is speculation based on VERY limited information. It could easily be wrong. That said, it does fit the given information, and - thus far - I haven't seen any information which directly contradicts the idea.
Either way, it is definitely a COOL thought! And if that IS what TWC has done, that would be *awesome*. It would make the Tricorder that much more functional/real.
No matter what, I *really* can't wait for this baby!