@m3moellering thanks! I sat on this for years (since 2018 or so), overthinking far too many details. How these old printers stored their fonts was utterly bonkers: 8 pins of one pass stored in one place, then 8 pins of the second stored somewhere completely else. There's a one bit field that tells you where to put the additional two pins, depending on whether the character has a descender or not. At least one character has this coded wrongly: semicolon sits on the baseline, not below it. But that's for someone else to fix
--somebody, for some reason