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Annotation of 43BSD/contrib/apl/doc/purdue, revision 1.1

1.1     ! root        1: .NH 2
        !             2: When is a ``Control-H'' not a backspace?
        !             3: .LP
        !             4: When it's an erase character.
        !             5: .PP
        !             6: By default,
        !             7: the Purdue Engineering Computer Network (ECN)
        !             8: \*u systems
        !             9: use the character
        !            10: ``control-H''
        !            11: as an erase character.
        !            12: (A ``control-H'' is typed by holding
        !            13: down the ``CTRL'' key and pressing
        !            14: an ``H''.)
        !            15: The ``erase'' character is a special
        !            16: character which tells the \*u
        !            17: operating system to back up one
        !            18: character on the line you are typing.
        !            19: Thus,
        !            20: if you mistype a letter,
        !            21: you can type the erase character
        !            22: (which will physically erase the
        !            23: previous character on the screen)
        !            24: and then type the correct character.
        !            25: .PP
        !            26: Unfortunately,
        !            27: \*a needs to use ``control-H''
        !            28: as a ``backspace'' character
        !            29: to produce overstrike symbols.
        !            30: If you are running \*a from
        !            31: a ASCII terminal,
        !            32: you will need to change your erase
        !            33: character to something other
        !            34: than ``control-H''.
        !            35: You can do this with the
        !            36: \fIstty\fR
        !            37: command.
        !            38: For example,
        !            39: to change your ``erase'' character to
        !            40: the underscore
        !            41: (which is not required in \*a),
        !            42: type:
        !            43: .sp
        !            44: $ stty erase \_
        !            45: .sp
        !            46: When you want to correct mistakes,
        !            47: type an underscore.
        !            48: When you want to type an
        !            49: overstrike symbol,
        !            50: type
        !            51: .sp
        !            52: <first char> <control-H> <second char>
        !            53: .sp
        !            54: Note that because of the way ASCII
        !            55: terminals are built,
        !            56: when you finish typing this
        !            57: only the second character will be visible.
        !            58: .PP
        !            59: From an \*a
        !            60: terminal
        !            61: things are a little easier.
        !            62: You may use the
        !            63: \fIstty\fR
        !            64: command to change your erase
        !            65: character,
        !            66: and you may use
        !            67: control-H as a backspace character.
        !            68: A better method,
        !            69: however,
        !            70: is to use the ``backspace'' key,
        !            71: located at the far right end
        !            72: of the keyboard
        !            73: (the key is marked ``^'' and ``~'').
        !            74: When you type:
        !            75: .sp
        !            76: <first char> <backspace> <second char>
        !            77: .sp
        !            78: the terminal will print the overstrike character
        !            79: on the screen.
        !            80: (Recall that ASCII terminals display only the
        !            81: second character.)
        !            82: .PP
        !            83: While we're on the subject of the
        !            84: ECN \*u \*a terminals,
        !            85: it would be a good idea to explain
        !            86: how to use the \*a character
        !            87: set.
        !            88: All public terminals are
        !            89: conventional ASCII terminals.
        !            90: A few,
        !            91: all currently located in the EE building,
        !            92: have been specially modified to
        !            93: use the \*a character set.
        !            94: These terminals can be distinguished
        !            95: from the others by the presence
        !            96: of a small switch on the left-hand
        !            97: side.
        !            98: When the switch is in the upward
        !            99: position,
        !           100: the terminal functions as an
        !           101: ASCII terminal.
        !           102: When the switch is set down,
        !           103: the terminal uses the
        !           104: \*a character set.

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