Is there any logic behind ASCII codes' ordering?

Question

I was teaching C to my younger brother studying engineering. I was explaining him how different data-types are actually stored in the memory. I explained him the logistics b

Answer 1

If you look at the binary representations for 'a' and 'A', you'll see that they only differ by 1 bit, which is pretty useful (turning upper case to lower case or vice-versa is just a matter of flipping a bit). Why start there specifically, I have no idea.