As the only exeption to this, where ASCII has the caret and the underscore at
0x5F , PETSCII has — still recognizable — an up-arrow and a left-arrow, respectively. (Apparently, since BACKSPACE became delete-to-the-left with common on-screen editors, the original ASCII glyphs weren’t found of much use without overprint capabilities…)
Actually, what Commodore has are the original ASCII characters, from ASCII-1963. The 1965 revision replaced
_. (There were a few other characters changed as well; you can see a table summarizing this at the bottom of my ASCII chart and the Wikpedia ASCII page has more details on the history of the standard.)
It’s not clear to my why Commodore, in 1976, went with ASCII-1963 rather than ASCII-1967. Maybe they just had only old reference books lying around?
A few years ago, on pagetable.com, Michael Steil speculated on why PETSCII has upper case and lower case reversed, though I think the comment on that post from Rhialto makes a more plausible case. I’ve also made a few notes on PETSCII for myself, with some references.