> the character you'd get on a traditional U.S. keyboard layout

I use a different layout so I'd never realised there was method to the madness! I get the following

$ echo -n ' !@#$%^&*(' | xxd -p 2021402324255e262a28

It’s more the old TTY layout which differs somewhat from the modified typewriter layout that’s become standard for computer keyboards. The old Apple ][ keyboard had 1–9 corresponding to the next row in ASCII, shift-0 was @, I think other characters were ±16 based on shift. Early ASCII implementations were often slightly inconsistent but codings were often based on keyboard layouts.

	▲	userbinator 7 days ago \| parent [-]
		The order of the punctuation descends from the very first typewriters, in the late 19th century: https://en.wikipedia.org/wiki/File:Remington_2_typewriter_ke...

▲

schoen 7 days ago | parent | prev [-]

The @ for shift-2 replaced the earlier " which you would see on many 1980s-era PCs.

I forget the story about what changed for shift-6 through shift-9.

When I say "traditional U.S. keyboard layout" I mean to contrast this with the modern one, which is the same as what you and I have.