For me its the ‘Knock Code’ that LG had on their phones (I really wish LG still made at least the V series phones)

Basically there was a four-square area and you set up a sequence of where you would tap to unlock the phone. That set of squares was only shown when you set up the code

Then, to unlock your phone, you would tap those areas in the sequence you set up (even with the screen off).

Fingerprint readers are nice, but I really do miss the knock code

Edit: did find this article with a way to do the knock code, but if done wrong, could brick your phone I guess.

Plus, article is from 2014. When I looked at XDA’s info on it (they also being the developers) it looks like development on it is over, but individual modules may or may not still be supported by their devs

  • zero_iq
    24•11 months ago

    Back in the day, I discovered I could i) print over IR to our office’s HP laser printer from my Psion organiser, ii) print control codes from the built-in OPL language to change the display message on the printer. I would occassionaly send messages like “insert coin”, “too much paper”, “grammatical error”, etc. when colleagues were printing.