3 ms·

> In the most popular character encoding, UTF-8, character number 65 ("A") is written: > 01000001 > Only the second and final bits are 1, or "on". Isn’t it m

> In the most popular character encoding, UTF-8, character number 65 ("A") is written: > 01000001 > Only the second and final bits are 1, or "on". Isn’t it more accurate to say that the first and penultimate bits are 1, or “on”?

fl7305 2y ago
It depends on whether your bit numbering is like x86 (your description), or PowerPC (left most bit is 0).
- duskwuff 2y ago
  Basically everyone uses x86 bit numbering. It has the pleasant property that the place value of every bit is always 2^n (or -2^n for a sign bit), and zero-extending a value doesn't change the numbering of its bits.
  - fl7305 2y ago
    Sure, it is by far the industry standard. It works much better for handling discrete integers. Once you get into bitfield instructions it is nice to have bit 0 be the "left most bit".
  - mark-r 2y ago
    It's a mistake to call it x86 bit numbering, it's way older than that.
- bandyaboot 2y ago
  The more I thought it through, even assuming x86, I guess there’s just no “correct” way to casually reference bit positions when we read them in the opposite order from the machine. Are they being referenced from the perspective of a human consumer of text, or the machine’s perspective as a consumer of bits? If I were writing that content, I’d have a difficult time deciding on which to use. If I were writing for a lay person, referencing left-to-right seems obvious, but in this case where the audience is primarily developers, it becomes much less obvious.
- mark-r 2y ago
  Thanks for giving me an example of an architecture where the bits are labelled backwards, I'd never encountered that before. I've always appreciated that the bit number represents 2 to the power of that number.
skerit 2y ago
This confused me too. Until reading this I didn't even think much about how I read binary numbers right-to-left by default.

fl7305 2y ago

It depends on whether your bit numbering is like x86 (your description), or PowerPC (left most bit is 0).

duskwuff 2y ago
Basically everyone uses x86 bit numbering. It has the pleasant property that the place value of every bit is always 2^n (or -2^n for a sign bit), and zero-extending a value doesn't change the numbering of its bits.
- fl7305 2y ago
  Sure, it is by far the industry standard. It works much better for handling discrete integers. Once you get into bitfield instructions it is nice to have bit 0 be the "left most bit".
- mark-r 2y ago
  It's a mistake to call it x86 bit numbering, it's way older than that.
bandyaboot 2y ago
The more I thought it through, even assuming x86, I guess there’s just no “correct” way to casually reference bit positions when we read them in the opposite order from the machine. Are they being referenced from the perspective of a human consumer of text, or the machine’s perspective as a consumer of bits? If I were writing that content, I’d have a difficult time deciding on which to use. If I were writing for a lay person, referencing left-to-right seems obvious, but in this case where the audience is primarily developers, it becomes much less obvious.
mark-r 2y ago
Thanks for giving me an example of an architecture where the bits are labelled backwards, I'd never encountered that before. I've always appreciated that the bit number represents 2 to the power of that number.

skerit 2y ago

This confused me too. Until reading this I didn't even think much about how I read binary numbers right-to-left by default.