It can display any single letter or number(Except K, V is forced to look like a U, and the Q looks weird because I need it to be different than a 9 so I can eventually develop a simple calculator)
Here's a screenie of it displaying an E:
I currently have a system in the works to build it as part of a memory delay grid, as well as adding in a redstone keyboard of sorts. I plan to eventually string a bunch of them together and either build them into a news ticker-like device, or a place to type things.
Each of the 8 segments(2 on each side, 1 on the top, 1 on the bottom, and 2 making up the cross in the center) can be turned on/off separately, letting me display a letter from 1 single byte of binary(8 binary states). The way I wish for it to work, 1 additional bit will be needed to signal that the 8 bits behind it need to be used to display a letter. All in all, I need 9 bits.