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  The first 32 ASCII characters, 00H through 1FH (decimal 0 through 31),
  have two important uses that just happen to conflict with each other. On
  one hand, these characters have standard ASCII meanings; they are used for
  both printer control (for example, ASCII 0CH (decimal 12) is the formfeed
  character) and communications control. On the other hand, IBM also uses
  them for some of the most interesting and useful display characters, such
  as the card-suit characters (hearts, diamonds, clubs, and spades)--ASCII
  03H through 06H, and the arrow characters (., ., ->, and .)--ASCII 18H
  through 1CH (decimal 24 through 27).

  When DOS transmits characters to the video screen or to a printer, it acts
  on the ASCII meaning of the characters instead of showing the character's
  picture. For example, the beep/bell character, ASCII 07H, has a dot for a
  picture. However, if you use DOS (or a programming language such as BASIC
  that relies on DOS for output), nothing happens on screen when you try to
  display this character: Instead, the speaker will beep. But if you put the
  character directly onto the screen by using the POKE command like this:

  DEF SEG = &HB800 : POKE 0, 7

  the character's picture will appear. You can always make characters appear
  on the screen by poking them into the screen buffer. However, it's much
  easier to use the PRINT statement to display characters. Store characters
  directly into the video buffer only if you can't display them with PRINT.

  Most of these 32 characters can be written to the screen, but the display
  characters may vary, depending upon which language is used. Figure C-5
  shows some of these differences. The characters not shown, ASCII 00H
  through 06H (decimal 0 through 6) and ASCII 0EH through 1BH (decimal 14
  through 27), can always be written to the screen with predictable results.

  ASCII Character                           Result
  Hex     Dec              In BASIC                In Most Other Languages
  --------------------------------------------------------------------------
  07H      7               Beeps                   Beeps
  08H      8               Character appears       Backspace action
  09H      9               Tab action              Tab action
  0AH     10               Linefeed and            Linefeed action
                           carriage-return action
  0BH     11               Cursor to top left      Character appears
  0CH     12               Screen clears           Character appears
  0DH     13               Carriage-return action  Carriage-return action
  1CH     28               Cursor moves right      Character appears
  1DH     29               Cursor moves left       Character appears
  1EH     30               Cursor moves up         Character appears
  1FH     31               Cursor moves down       Character appears
  --------------------------------------------------------------------------

  Figure C-5.  The results obtained when certain characters are written to
  the screen using different languages.