It is a 7-bit code.
Many 8-bit codes (e.g., ISO 8859-1) contain ASCII as their lower half.
The international counterpart of ASCII is known as ISO 646-IRV.
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The following table contains the 128 ASCII characters.
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C program \f(CW\(aq\eX\(aq\fP escapes are noted.
.if t \{\
.ft CW
An
.B ascii
manual page appeared in Version 7 of AT&T UNIX.
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On older terminals, the underscore code is displayed as a left arrow,
called backarrow, the caret is displayed as an up-arrow and the vertical
bar has a hole in the middle.
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Uppercase and lowercase characters differ by just one bit and the
ASCII character 2 differs from the double quote by just one bit, too.
That made it much easier to encode characters mechanically or with a
non-microcontroller-based electronic keyboard and that pairing was found
on old teletypes.
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The ASCII standard was published by the United States of America
Standards Institute (USASI) in 1968.
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