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I stumbled across the history of the ASCII "delete" character recently: It's character 127, which means it's 1111111 in binary. On paper tape, that translates into 7 holes, meaning any other character can be "deleted" on the tape by punching out its remaining holes.

(It's also the only non-control ASCII character that can't be typed on an English keyboard, so it's good for creating WIFi passwords that your kid can't trivially steal.)




> It's also the only non-control ASCII character that can't be typed on an English keyboard

Don't count on it. There's a fairly long standing convention in some countries with some keyboard layouts that Control+Backspace is DEL. This is the case for Microsoft Windows' UK Extended layout, for example.

    [C:\]inkey Press Control+Backspace %%i & echo %@ascii[%i]
    Press Control+BackspaceāŒ‚
    127
    
    [C:\]
This is also the case for the UK keyboard maps on FreeBSD/TrueOS. (For syscons/vt at least. X11 is a different ballgame, and the nosh user-space virtual terminal subsystem has the DEC VT programmable backspace key mechanism.)


Wow, I never knew it was an actual character.


Sure, think of it this way: you're sitting at a terminal connected to a mainframe and press the "X" key; what bits get sent over the wire? The ones corresponding to that letter on the ASCII chart.

Now replace "X" with "Delete".


It's actually easier to add two spaces at both ends of the password :)




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