Mark E. Shoulson <mark at kli dot org> wrote: > I remember my old TRS-80 had double-quotes on shift-2 as well. I > half-remember that it had something to do with the bit-patterns, so > the shift key could work by applying a fairly trivial transformation > to the unshifted characters. "2" is 0032 and """ is 0022, so I may > not be completely mistaken... yeah, I think it looks right: the rest > of the shifted-number symbols match the number symbols minus 0010.
This was the standard typewriter arrangement, which in turn was actually the reason why that pair (and others) differs by only one bit in ASCII. Mackenzie (1980) noted that Criterion 17 for determining code positions in the original ASCII was that "Graphics that are normally paired on typewriter keytops should differ in only a common single bit position." Interestingly, a few pages later he described the assignment of ! and " to positions 2/1 and 2/2 as "more or less arbitrary," even though those two did satisfy Criterion 17. As Frank said, it's a fascinating book for character geeks. Unfortunately, it's long out of print and has to be special-ordered, and isn't cheap; my slightly used copy cost me 67 USD four years ago. -Doug Ewell Fullerton, California http://users.adelphia.net/~dewell/
