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american standard code for information interchange
(msas) | American Standard Code for Information Interchange
- ASCII |
american standard code for information interchange
(msasasci) | American Standard Code for Information Interchange
- ASCII |
american standard code for information interchange
(czen) | American Standard Code for Information Interchange,ASCIIn: [zkr.]
[it.] kód, ve kterém jsou znaky reprezentovány čísly od 0 do 127 Petr
Prášek |
american standard code for information interchange
(wn) | American Standard Code for Information Interchange
n 1: (computer science) a code for information exchange between
computers made by different companies; a string of 7 binary
digits represents each character; used in most
microcomputers [syn: {American Standard Code for
Information Interchange}, ASCII] |
american standard code for information interchange
(foldoc) | American Standard Code for Information Interchange
ASCII
The basis of character sets used in almost
all present-day computers. US-ASCII uses only the lower seven
bits (character points 0 to 127) to convey some {control
codes}, space, numbers, most basic punctuation, and unaccented
letters a-z and A-Z. More modern coded character sets (e.g.,
Latin-1, Unicode) define extensions to ASCII for values above
127 for conveying special Latin characters (like accented
characters, or German ess-tsett), characters from non-Latin
writing systems (e.g., Cyrillic, or Han characters), and such
desirable glyphs as distinct open- and close-quotation marks.
ASCII replaced earlier systems such as EBCDIC and Baudot,
which used fewer bytes, but were each broken in their own way.
Computers are much pickier about spelling than humans; thus,
hackers need to be very precise when talking about characters,
and have developed a considerable amount of verbal shorthand for
them. Every character has one or more names - some formal, some
concise, some silly.
Individual characters are listed in this dictionary with
alternative names from revision 2.3 of the Usenet ASCII
pronunciation guide in rough order of popularity, including
their official ITU-T names and the particularly silly names
introduced by INTERCAL.
See V ampersand, asterisk, back quote, backslash,
caret, colon, comma, commercial at, control-C,
dollar, dot, double quote, equals, exclamation mark,
greater than, hash, left bracket, left parenthesis,
less than, minus, parentheses, oblique stroke,
percent, plus, question mark, right brace, {right
brace}, right bracket, right parenthesis, semicolon,
single quote, space, tilde, underscore, {vertical
bar}, zero.
Some other common usages cause odd overlaps. The "#", "$", ">",
and "&" characters, for example, were all pronounced "hex" in
different communities because various assemblers use them as a
prefix tag for hexadecimal constants (in particular, "#" in many
assembler-programming cultures, "$" in the 6502 world, ">" at
Texas Instruments, and "&" on the BBC Micro, {Acorn
Archimedes}, Sinclair, and some Zilog Z80 machines). See also
splat.
The inability of US-ASCII to correctly represent nearly any
language other than English became an obvious and intolerable
misfeature as computer use outside the US and UK became the rule
rather than the exception (see software rot). And so national
extensions to US-ASCII were developed, such as Latin-1.
Hardware and software from the US continued for some time to
embody the assumption that US-ASCII is the universal character set
and that words of text consist entirely of byte values 65-90 and
97-122 (A-Z and a-z); this is a major irritant to people who want
to use a character set suited to their own languages. Perversely,
though, efforts to solve this problem by proliferating sets of
national characters produced an evolutionary pressure (especially
in protocol design, e.g., the URL standard) to stick to
US-ASCII as a subset common to all those in use, and therefore
to stick to English as the language encodable with the common
subset of all the ASCII dialects. This basic problem with having
a multiplicity of national character sets ended up being a prime
justification for Unicode, which was designed, ostensibly, to be
the *one* ASCII extension anyone will need.
A system is described as "eight-bit clean" if it doesn't
mangle text with byte values above 127, as some older systems
did.
See also ASCII character table, Yu-Shiang Whole Fish.
(2014-10-05)
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