This is a very rare DL-3422 intelligent alphanumeric display: it seems to only have been produced for a couple of years in the early 1980s and there is no information about it on the internet. This is not a 16-segment display: it's a 22-segment display, possibly the only one ever created. The extra segments are used to show lowercase letters: the DL-3422 has an 7-bit ASCII decoder and full uppercase and lowercase character sets. I found it in a box full of other displays at a surplus store, I have no idea if they can be bought anywhere else. I scanned the datasheet from a book and posted it online, because if it's not on the internet, it can't be true! Here's a closeup photo of the characters: If anyone has more information about this mysterious part, I'd love to hear it!