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The Elegance of the ASCII Table

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Re: The Elegance of the ASCII Table

#141

Post by w0m »

INTPenis wrote: post #88
augusto-moura wrote: post #67

Useful tip, on linux (not sure about other *nixes) you can view the ascii table by opening its manpage: man ascii It's been useful to me more than once every year, mostly to know about shell escape codes and when doing weird character ranges in regex and C. It can be a bit confusing, but the gist is that you have 2 chars being show in each line, I would prefer a view where you see the same char with shift and/or ctrl…

The reason I know this is because in 2004 I was squatting in an apartment with no TV and no internet. So each day after work I would go home and just read manpages for fun. Ended up learning ipfw through the firewall manpage on FreeBSD, and using my skills to setup and manage an IPFW at work. It's amazing how much you get done with no TV and no internet. Also played a lot of nethack.

I learned vim proper by reading :help on an eeepc while flying back and forth over the Atlantic alone one year.

Re: The Elegance of the ASCII Table

#142

Post by 91bananas »

kragen wrote: post #32
jolmg wrote: post #10

> So when you’re reading 7-bit ASCII, if it starts with 00, it’s a non-printing character. Otherwise it’s a printing character. > The first printing character is space; it’s an invisible character, but it’s still one that has meaning to humans, so it’s not a control character (this sounds obvious today, but it was actually the source of some semantic argument when the ASCII standard was first being discussed). Hmm..…

del is not a printing character. it's a control character. if you run a paper tape full of del characters through a teletype it does not print anything. it has to have that bit pattern, even though it greatly complicates the mechanics of the teletype (which has to do all the digital logic with cams and levers) because that way it can be punched over any character on the paper tape to delete it a figure caption in thi…

just... this is why this forum exists. thank you

Re: The Elegance of the ASCII Table

#143

Post by shepherdjerred »

WalterBright wrote: post #52

Too bad we now have Unicode, an elegant castle covered with ugly graffiti and ramshackle addons. For example: 1. normalization 2. backwards running text (hey, why not add spiral running text?) 3. fonts 4. invisible characters 5. multiple code points with the same glyph 6. glyphs defined by multiple code points (gee, I thought Unicode was to get away with that mess from code pages!) 7. made up languages (Elvish? Come…

What would be the alternative? I think Unicode is pretty great.

You can pretty easily imagine a world where we had a bunch of different encodings with none being dominant.

Re: The Elegance of the ASCII Table

#145

Post by kragen »

91bananas wrote: post #142
kragen wrote: post #32

Earlier quoted context omitted.

del is not a printing character. it's a control character. if you run a paper tape full of del characters through a teletype it does not print anything. it has to have that bit pattern, even though it greatly complicates the mechanics of the teletype (which has to do all the digital logic with cams and levers) because that way it can be punched over any character on the paper tape to delete it a figure caption in thi…

just... this is why this forum exists. thank you

you're welcome. i'll try to remember your comment the next time someone replies to me with something like https://news.ycombinator.com/item?id=40993821 or https://news.ycombinator.com/item?id=40993328 or https://news.ycombinator.com/item?id=40992456

Re: The Elegance of the ASCII Table

#147

Post by theamk »

jiveturkey wrote: post #139
theamk wrote: post #31

Earlier quoted context omitted.

It's really not. In base-2 machines, the letters are mixed with punctuation, which is pretty horrible design which makes simple things complex, and does not actually bring anything new to the table. In BCD machines it is slightly better, except letters aren't contiguous either - row 0 is bad, but it's the extra space between R and S which is really ugly. And it's unusable with BCD operations anyway, as high nibble va…

It was designed for a specific purpose ... elegance in context

Which would that "specific purpose" be? Even punch cards have alphabet interrupted between R and S.

And the whole punch card -> 8-bit is pretty illogical, just like the cards themselves. How come no punches in zone don't correspond to 0 high bits?

(and don't get me started on punch card.. it started with "let's do 1 hole per column for digits" - OK, makes sense; then "let's do 2 hole/column for uppercase" - I guess OK but why did you put extra char in the middle... but then it's 4 holes/column for superscripts? 3-6 holes/col for punctuation? If someone were to design punch cards today but using same requirements, they could easily come up with a much more logical schema)

Re: The Elegance of the ASCII Table

#148

Post by Findecanor »

flohofwoe wrote: post #133
Sharlin wrote: post #72

Earlier quoted context omitted.

Yes, that’s very intentional and just masking (or setting) the bit is the intended way to do case-insensitive comparison of the letter range in ASCII (eg. stricmp in C), or to transform text to lower or upper case (tolower, toupper). But what’s more, ever wondered whence the control (Ctrl) key presses like Ctrl-H to backspace, or Ctrl-M for carriage return? Well, inspecting the ASCII chart it becomes evident: the Ctr…

...it's a bit of a shame that the same upper/lowercase trick doesn't apply to all UNICODE codepoints (at least those that have upper/lower variants). It seems to work for codepoints up to U+00FF, for instance: - Å (U+00C5) vs å (U+00E5) ...but above 0xFF lowercase follows uppercase: - Ă (U+0102) vs ă (U+0103) Typical for UNICODE though, nothing makes sense ;)

That's because U+00A0–U+00FF are encoding an earlier character set: "ISO Latin-1" (ISO 8859-1), itself based on DEC's "Multinational Character Set". The upper/lowercase trick does not apply to ß/ÿ but does in MCS where Ÿ/ÿ are at a different pair of code points.

ISO Latin-1 was the character set on many Unix systems, Amiga OS, MS-Windows (as "Windows-1252" with extra chars), and was for many years the default character set on the web.

Re: The Elegance of the ASCII Table

#149

Post by Dylan16807 »

p_l wrote: post #138
news_to_me wrote: post #119

Earlier quoted context omitted.

> "a + ogonek accent" and another (properly) sent "a with ogonek" (these print the same but are semantically different!) How can these possibly be semantically different? Isn’t the point of combining characters to create semantic characters that are the combination of those parts?

There's a semantic difference between "accented letter" and "different letter that happens to visually look like another language's accented letter". "Ą" in polish is not "A" with some accent. And the idea behind unicode was to preserve human written text, including keeping track of things like "this is letter A1 with an accent, but this is letter A2 that looks visually similar to A1 with accent but is different sema…

Unless there's some nuance I'm missing, I think you're reading too much into the word "accent".

Especially because the codepoint is actually called "Combining Ogonek".

And for anyone writing in Cyrillic, it's actually more accurate to use the combining form, even as its own letter, because the only precomposed form technically uses a latin A.

But my main point is that I do not think there is supposed to be any semantic difference in Unicode based on whether you use precomposed or decomposed code points.

Re: The Elegance of the ASCII Table

#150

Post by irrational »

augusto-moura wrote: post #67

Useful tip, on linux (not sure about other *nixes) you can view the ascii table by opening its manpage: man ascii It's been useful to me more than once every year, mostly to know about shell escape codes and when doing weird character ranges in regex and C. It can be a bit confusing, but the gist is that you have 2 chars being show in each line, I would prefer a view where you see the same char with shift and/or ctrl…

Works on mac
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