[atsaloli]

Nice. Reminds me of the explanation why the code for DEL (delete) in ASCII is 127 (1111111) -- back in the days of punchcards, when a punched hole meant "one" and no hole meant "zero", you could convert any other code into 1111111 by overstriking it (similar to how in the days of typewriters you could overstrike any other letter with X to cross it out).

[drfuchs]

Close, but that only worked for punched paper tape (which had 7 positions for hole / not-hole per row, with a direct mapping to ASCII). Punch cards used Hollerith code, with 12 positions per column, with a peculiar mapping to EBCDIC, where there would be only one hole in rows 1 to 8, which more or less gave the bottom 3 bits of the character, and a combination of holes in the other 4 rows, giving the other 4 bits.

[atsaloli]

Thank you!