R: ASCII

["Adriano Ortile" md4929@xxxxxxxx]

Carlo Caballero wrote:
> I wonder if someone who is more expert on character sets than I would
like
> to comment on how the documentation for XyWrite--among many other
> sources--came to call "ASCII" all those varied extensions of the original
> US-ASCII? What, then is *not* "ASCII" (in the loose sense of the XyWrite
> manuals)? I've always been suspicious of the term "control codes" and
> would welcome some precision.
>
Many and many and many years ago, the ASCII set (the original one)
comprehended only the first 128 characters, the first 31 of them used for
control: code 2 for STX (Start-Of-Text), code 3 for ETX (End-Of-Text), code
7 for Bell, code 8 for Backspace, etc. Code 10 for LF (Line-Feed) and code
13 for CR (Carriage-Return), as today some time... It was a 7-bit code; the
eighth bit was used for parity check. On the teletypes, you had to strike
bothe CR and LF keys to go to the initial point of the next line; striking
the LF alone was causing the paper to be moved upward for next line to be
printed, leaving the head on the same column position; striking the CR
alone was causing the head to go to the beginning of the same line.
When introduced its PC (1980?), IBM extended the use of the ASCII code to
the full 256 combinations: the eighth bit became an added bit and was not
longer used as parity check. This code has been called Extended ASCII.
There was not Code Page. Instead, initially this caused confusion: some
manufacturers were using the high part of code for different purposes:
Epson, for example, was using some upper codes for change the printed
characters from standard to italic.
Day after day, the extended ASCI became de facto "the" ASCII.
Later, the upper 128 characters were used in attempting to satisfy needs
for different uses and countries. A sort of anarchy, as we know today.
And later more, the 256 characters became unsatisfactory, so now a single
byte is not enough to describe a single character.
Why XyWrite is a pure ASCII text editor? Having been developed to be used
on a IBM PC, it was designed to use "all" of the 256 characters, but,
differently from other word processors, it does not put strange algorithms
and codes into the text you write: if you "type" your text ("type" is a DOS
command to print on the screen), you see on the screen exactly the text you
wrote. This is not true, for example, for Word.
Regards
Adriano Ortile
ortile@xxxxxxxx