A little under two months ago I invested in an expensive ergonomic keyboard, a Kinesis Advantage 2, and set about figuring out how to use it most effectively with Emacs. The default layout for the keyboard is great for strong typists who control their computer mostly with their mouse, but less good for Emacs users, who are strong typists that control their computer mostly with their keyboard.

It took me several tries to figure out where to put the ctrl, alt, backspace, delete, return and spacebar keys, and aside from one forum post I ran into, I haven’t found anyone online who came up with anything much like what I’ve come up with, so I thought I should probably write up a blog post.

The mappings: Kinesis Advantage 2

The pairs of arrow keys under the first two fingers of each hand become ctrl and alt/meta keys. This way there is a ctrl and alt/meta key for each hand, to reduce the need for one-handed chording.

I bought the keyboard expecting to have all modifier keys on my thumbs. However, (i) only the two large thumb keys can be pressed without lifting your hand away from the home row, or stretching in a way that’s not healthy; and (ii) only the outermost large thumb key can be comfortably held down as a modifier.

It takes a little work to get used to using the third and fifth fingers of one hand to hold down both alt/meta and shift, for typing core Emacs commands like M-^ and M-@, but it does become natural to do so.
The arrow keys are moved to the four ctrl/alt/super keys which run along the top of the thumb key areas.
The outermost large thumb key of each hand becomes a spacebar. This means it is easy to type C-u C-SPC with the right hand while the left hand holds down control, and sequences like C-x C-SPC and C-a C-SPC C-e with the left hand with the right hand holding down control.

It took me a while to realise that it is not wasteful to have two spacebars.
The inner large thumb keys become backspace and return.
The international key becomes delete, and remains insert on the keypad layer.

Delete is rarely needed for Emacs users, as we have C-d, so initially I just had no delete key, but soon came to regret this when trying to edit text in web forms.
Caps Lock becomes Super, but remains caps lock on the keypad layer.

See my rebindings for ordinary keyboards for some discussion of having just a single Super key.
Backtick becomes an additional escape on the keypad layer.

The mappings: Kinesis Advantage360

As above, except

”Caps Lock” means the key labelled “Esc” and “the international key” means the key labelled “Caps Lock”
Fn+Caps Lock (Fn+”Esc”) becomes an additional caps lock
Fn+International key (Fn+”Caps Lock”) becomes an additional insert
Fn+backtick becomes an additional escape.

When escape or insert must be typed shift-modified, e.g. Shift+Insert, use the keypad layer mappings, not the Fn1 layer mappings.

I would also suggest mapping ①, ②, ③ and ④ to F5, F6, F7, and F8, which are reserved to users by the Emacs Lisp key binding conventions, and are less easy to access on the Advantage360 with its lack of dedicated function keys. And indeed, one standard usage for these keys in Emacs is user-recorded keyboard macros; see C-x C-k b. Rather than letting them have their own key codes or using the keyboard firmware’s own facility for keyboard macros, just mapping the four keys to ordinary function keys means you can use them to hold ad hoc keyboard macros in text mode Emacs frames too.

Sequences of two modified keys on different halves of the keyboard

It is desirable to input sequences like C-x C-o without switching which hand is holding the control key. This requires one-handed chording, but this is trecherous when the modifier keys not under the thumbs, because you might need to press the modified key with the same finger that’s holding the modifier!

Fortunately, most or all sequences of two keys modified by ctrl or alt/meta, where each of the two modifier keys is typed by a different hand, begin with C-c, C-x or M-g, and the left hand can handle each of these on its own. This leaves the right hand completely free to hit the second modified key while the left hand continues to hold down the modifier.

My rebindings for ordinary keyboards

I have some rebindings to make Emacs usage more ergonomic on an ordinary keyboard. So far, my Kinesis Advantage setup is close enough to that setup that I’m not having difficulty switching back and forth from my laptop keyboard.

The main difference is for sequences of two modified keys on different halves of the keyboard – which of the two modified keys is easiest to type as a one-handed chord is different on the Kinesis Advantage than on my laptop keyboard. At this point, I’m executing these sequences without any special thought, and they’re rare enough that I don’t think I need to try to determine what would be the most ergonomic way to handle them.

Update 20/viii/2022: Added Advantage360 mappings.