What are the fonts used in MCDU screens? All MCDUs (and other screens) I've seen share a very similar, if not identical, set of fonts - a monospaced, sans-serif, very clean and easily readable font, often in two vertical sizes at the same horizontal pitch. What font is that? Do different instrument/airplane makers have their own? Do airlines standardize on one across their fleets?
FAA's Advisor Circular 25-11b (https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25-11B.pdf) makes some recommendations on fonts.
Also, http://www.b737.org.uk/fmc.htm has screen photos where the pixels are discernible, presumably from an early 737 model. There isn't a name, but there is enough unique features for it to be identified, if it has an official name.
My guess is that these are raster (non-scalable) fonts without any special name.

At least initially, the screen resolution wasn't (and needed not be) particularly high, and the characters were the typical 8x8 pixels or only slightly better. Such fonts are drawn by hand (by pixel) and don't have too many variations to speak about. (Although the sales people might disagree).

Later models with higher-resolution screens probably modeled the same terminal-type font to keep commonality. I still doubt MCDUs have an operating system (if any) with scalable font support.