Via https://news.ycombinator.com/item?id=46470339

I wish someone would do the same for the VT525. The last DEC terminal, it is close to a superset of the preceding ones (ignoring some features that were dropped) and those of a bunch of other vendors too

I got Tetris to stop a block before it reached the bottom by holding "down". Not every time, just a couple of times.

Wow. I used one of these as an “upgrade” to a VT220. I am very much tempted to bolt a Pi Zero to a display and dedicate it to running just this, with that font, and a finely calibrated amber color (maybe I can hack a shader for extra retro).

Lol. Disassembled the VT420 ROM's and slapped a AGPL license on it. It's probably okay. I don't think anyone at HP remembers they once owned the DEC IP (or which of the HP spin-offs kept the DEC/COMPAQ IP, HPE?) And forgiveness instead of permission is usually the way to go. Just sort of hilarious you're stealing someone's IP and slapping a restrictive license on it.

EDIT: Let me also say, this is awesome. Don't let my "tsk tsk" paragraph above imply that I do not fully support this project and consider it cool.