Bytes and octets

From: Hans Aberg (haberg@math.su.se)
Date: Wed Apr 15 2009 - 03:00:48 CDT

  • Next message: Hans Aberg: "Uncommon bytes"

    On 12 Apr 2009, at 23:05, Philippe Verdy wrote:

    > Actually there's a differnce between the two encoding schemes:
    > - UTF-8 assumes that "bytes" can contain at least 8 significant bits
    > and it
    > assigns specific meaning to the 8th bit, but does not assume
    > anything for
    > possible extra bits that be left used after the 8 lowest bits in the
    > same
    > adressable unit of memory (a byte is not necessarily 8-bit wide;
    > think about
    > it as if we hd used the term "code unit" for "byte"; in fact two
    > bytes may
    > also not be separated by 1 increment of addressable memory, because
    > 1-bit
    > memory also exists, even if, today, mst systems have adopted alignment
    > constraints for blocks of succesive bits making a single byte).
    > - ASCII just assumes that "bytes" can contain at least 7 significant
    > bits
    > (but it indicates absolutely nothing for code units that are not in
    > the
    > range 0 to 127.

    In fact, computer standards that require exactly 8 bits may use the
    word "octet"
       http://en.wikipedia.org/wiki/Octet_(computing)
    The link says the word is commonly used in France, among other places.

       Hans



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