On Tue, 30 Aug 2011, Paul Erkens wrote:
But what I never understood was the unicode thing you mention. Is unicode sort of an extended version of ascii?
Unicode is the idea that all possible symbols can be represented in the same character set.
As you identified in your message, there are only 256 possible symbols in the ASCII character set, 255 if you don't include the null character which is number 0. But US-ASCII is only one of literally hundreds of character sets that can be used to encode text. All these other character sets came into being because of the large and varying range of symbols which needed to be encoded.
As this thread has demonstrated, switching between character sets is annoying at best. Life would be a lot simpler if you could simply just use one character set for everything and not have to change anything. And this is what Unicode is trying to do.
When people talk about Unicode, they're usually talking about the character set called UTF-8. This is the most commonly used character encoding that tries to meet the goals of Unicode.
UTF-8 is a super-set of ASCII. All standard latin alpha-numeric characters and punctuation symbols are represented in exactly the same way as they are in ASCII, making it backward-compatible in a number of settings.
For other symbols, UTF-8 uses up to 4 bytes to encode a character, thereby getting around the limit of 256. The use of up to 4 bytes is presumably to avoid ambiguity.
For more information on Unicode and the various ways of representing it, see http://en.wikipedia.org/wiki/Unicode
To what extent does the ascii table relate to a braille table, and what exactly is unicode and how does that get translated to a unicode braille table?
The references to ASCII and Unicode in relation to Braille tables refers to the symbols that are to be translated. Standard 6-dot Braille is, by its nature, a 6-bit system, and even 8-dot Braille only needs 8 bits. So Braille itself only needs at most one byte per character.
A Unicode Braille table is able to display representations of Unicode text without the need to change Braille tables for each represented language.
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