( c-addr u
is greater than zero, display the character string
specified by c-addr
When passed a character in a character string whose
character-defining bits have a value between hex 20 and 7E
inclusive, the corresponding standard character, specified
by 220.127.116.11 Graphic characters
, is displayed.
Because different output devices can respond differently to
control characters, programs that use control characters to
perform specific functions have an environmental dependency.