1. <operating system> (Or "erase") To make a file
inaccessible.
Usually this operation only deletes information from the
tables the file system uses to locate named files; the
file's contents still exist on disk and can sometimes be
recovered by scanning the whole disk for strings which are
known to have been in the file. Files created subsequently on
the same disk are quite likely to reuse the same blocks and
thus overwrite the deleted file's data permanently.
2. <character> The control character with ASCII code 127.
Usually entering this character from the keyboard deletes the
last character typed from the input buffer. Sadly there is
great confusion between operating systems and keyboard
manufacturers as to whether this function should be assigned
to the delete or backspace key/character.
The choice of code 127 (binary 1111111) is not arbitrary but
dates back to the use of paper tape for input. The delete
key rewound the tape by one character and punched out all
seven holes, thus obliterating whatever character was there
before. The tape reading software ignored any delete
characters in the input.
