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(emacs)Single-Byte Character Support

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Single-byte Character Set Support
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   The ISO 8859 Latin-N character sets define character codes in the
range 0240 to 0377 octal (160 to 255 decimal) to handle the accented
letters and punctuation needed by various European languages (and some
non-European ones).  If you disable multibyte characters, Emacs can
still handle _one_ of these character codes at a time.  To specify
_which_ of these codes to use, invoke `M-x set-language-environment'
and specify a suitable language environment such as `Latin-N'.

   For more information about unibyte operation, see Note: Enabling
Multibyte.  Note particularly that you probably want to ensure that
your initialization files are read as unibyte if they contain non-ASCII
characters.

   Emacs can also display those characters, provided the terminal or
font in use supports them.  This works automatically.  Alternatively,
if you are using a window system, Emacs can also display single-byte
characters through fontsets, in effect by displaying the equivalent
multibyte characters according to the current language environment.  To
request this, set the variable
`unibyte-display-via-language-environment' to a non-`nil' value.

   If your terminal does not support display of the Latin-1 character
set, Emacs can display these characters as ASCII sequences which at
least give you a clear idea of what the characters are.  To do this,
load the library `iso-ascii'.  Similar libraries for other Latin-N
character sets could be implemented, but we don't have them yet.

   Normally non-ISO-8859 characters (decimal codes between 128 and 159
inclusive) are displayed as octal escapes.  You can change this for
non-standard "extended" versions of ISO-8859 character sets by using the
function `standard-display-8bit' in the `disp-table' library.

   There are several ways you can input single-byte non-ASCII
characters:

   * If your keyboard can generate character codes 128 (decimal) and up,
     representing non-ASCII characters, you can type those character
     codes directly.

     On a windowing terminal, you should not need to do anything
     special to use these keys; they should simply work.  On a
     text-only terminal, you should use the command `M-x
     set-keyboard-coding-system' or the Custom option
     `keyboard-coding-system' to specify which coding system your
     keyboard uses (Note: Specify Coding).  Enabling this feature
     will probably require you to use `ESC' to type Meta characters;
     however, on a Linux console or in `xterm', you can arrange for
     Meta to be converted to `ESC' and still be able type 8-bit
     characters present directly on the keyboard or using `Compose' or
     `AltGr' keys.  Note: User Input.

   * You can use an input method for the selected language environment.
     Note: Input Methods.  When you use an input method in a unibyte
     buffer, the non-ASCII character you specify with it is converted
     to unibyte.

   * For Latin-1 only, you can use the key `C-x 8' as a "compose
     character" prefix for entry of non-ASCII Latin-1 printing
     characters.  `C-x 8' is good for insertion (in the minibuffer as
     well as other buffers), for searching, and in any other context
     where a key sequence is allowed.

     `C-x 8' works by loading the `iso-transl' library.  Once that
     library is loaded, the <ALT> modifier key, if you have one, serves
     the same purpose as `C-x 8'; use <ALT> together with an accent
     character to modify the following letter.  In addition, if you
     have keys for the Latin-1 "dead accent characters," they too are
     defined to compose with the following character, once `iso-transl'
     is loaded.  Use `C-x 8 C-h' to list the available translations as
     mnemonic command names.

   * For Latin-1, Latin-2 and Latin-3, `M-x iso-accents-mode' enables a
     minor mode that works much like the `latin-1-prefix' input method,
     but does not depend on having the input methods installed.  This
     mode is buffer-local.  It can be customized for various languages
     with `M-x iso-accents-customize'.