Alt (assuming you actually mean Meta ;) is completely unnecessary for emacs. Meta-<Key> can always be produced by pressing ESC <Key>

I guess technically ctrl is also unnecessary since you could type out whole commands with M-x (ESC x command). It wouldn't be fun, but you could do it.

Although most keyboards nowadays use Alt for Meta, they were distinct keys on some older keyboards. I personally never used an MIT Lisp machine, but I have used Sun keyboards with a Meta key.

It's also fun to note that EMACS is an acronym for Escape Meta Alt Control Shift, which generally describes the experience of using it.

As joke acronyms go, I preferred "Eight Megs And Constantly Swapping" back when Eight Megs was a lot of memory. "Eighty Megs" worked for a while after that. These days you'd have to rename it EGACS to use that joke.

Actually, it stood for "Editing MACroS" [1]. There are other expansions though -- see [2] below.

[1] http://www.gnu.org/software/emacs/emacs-faq.html#Origin-of-t...

[2] http://www.gnu.org/fun/jokes/gnuemacs.acro.exp.html

Also there is the totally useless capslock key, it could be mapped to meta just fine ^_^

See point 1 on Steve Yeggies's list of things to consider with emacs.

https://sites.google.com/site/steveyegge2/effective-emacs

Maybe his keyboard is modal, but we never see it change. ;)

http://emacswiki.org/emacs/FootSwitches :)

He could have remapped the keys arbitrarily, and he also could have used unicode input methods to type | with more than one keystroke.

For what it is worth I use an "otaku" Happy Hacking KeyBoard Pro 2 (HHKB Pro 2) with "blank" black keys and I remapped | to HYPER+[ (and I'm of course using right alt as a "new" modifier, HYPER).

tl;dr: you can't never be sure how Emacs hacker have configured their keys/modifiers ; )