del is not a printing character. it's a control character. if you run a paper tape full of del characters through a teletype it does not print anything. it has to have that bit pattern, even though it greatly complicates the mechanics of the teletype (which has to do all the digital logic with cams and levers) because that way it can be punched over any character on the paper tape to delete it
a figure caption in this page says 'This is a historical throwback to paper tape, where the keyboard would punch some permutation of seven holes to represent the ones and zeros of each character. You can’t delete holes once they’ve been punched, so the only way to mark a character as invalid was to rewind the tape and punch out all the holes in that position: i.e. all 1s.' which is mostly correct, except that it wasn't a historical throwback; paper tape was perhaps the most important medium for ascii not just in 01963 and 01967 but probably in 01973, maybe even in 01977. teletype owners today are still using paper tape that was manufactured during the vietnam war, where it was used in unprecedented volume for routing teletype messages by hand
the dominant early pc operating system, cp/m (if it's not overly grandiose to call it an 'operating system') had system calls for reading and writing the console, the disk, and the paper tape punch and reader. when i hooked up a modem to my cp/m system to call bbses, i hooked it up as the punch and reader
wow, i sure didn't have to wait long; in this case it's someone who's harassed me repeatedly and who uses the site mostly for political flamewars: https://news.ycombinator.com/item?id=41056718
a figure caption in this page says 'This is a historical throwback to paper tape, where the keyboard would punch some permutation of seven holes to represent the ones and zeros of each character. You can’t delete holes once they’ve been punched, so the only way to mark a character as invalid was to rewind the tape and punch out all the holes in that position: i.e. all 1s.' which is mostly correct, except that it wasn't a historical throwback; paper tape was perhaps the most important medium for ascii not just in 01963 and 01967 but probably in 01973, maybe even in 01977. teletype owners today are still using paper tape that was manufactured during the vietnam war, where it was used in unprecedented volume for routing teletype messages by hand
the dominant early pc operating system, cp/m (if it's not overly grandiose to call it an 'operating system') had system calls for reading and writing the console, the disk, and the paper tape punch and reader. when i hooked up a modem to my cp/m system to call bbses, i hooked it up as the punch and reader