I think I’m done designing my layout in basic terms (I’m MP4 so I’m ramping up my preparations for hopefully imminent shipping). I haven’t really worked out positions of character keys so well yet, but I have a fair idea about them.
This isn’t something which has taken that much effort really, once I got my thoughts together about it. I’m not too fussy about completely optimising everything, since just about anything which tries to prioritise keys based on frequency of use and avoiding digraph usage on single fingers is pretty reasonable, and miles ahead of qwerty. So instead I decided to be pragmatic about that and prioritise something else:
Many non-qwerty layouts preserve zxcv for ctrl shortcuts, which makes a lot of sense as they are ingrained in many people where they are, are already in logical spots as rarely used letters (except c maybe) but more importantly, they are great to use with the left hand only while the right uses the mouse to highlight what’s being cut/copy/pasted (and undone). But why stop there? There are a heap of shortcuts I use (or want to start using) while using the mouse at the same time. asdfbuity also get put on the left hand for this reason, and therefore eonrhlmpgwkjq make up the right hand (13 each), which splits the most commonly used letters in english remarkably evenly for a purely non-linguistic choice of distribution! (I actually don’t really care as much as many people about hand use balance, but it’s nice nonetheless - certainly in qwerty the right hand is horribly underused)
Given that, I assigned tentative spots for each letter based on frequency of use and finger comfort. 2345 finger home row spots were most prioritised, then 234 upper row spots and adjacent to 2 on the home row, then 2345 bottom row, and finally 5 on the upper row. This is personal to me, and the last may change depending on how comfortable I feel reaching the keys on the t and y positions in the default layout. Regardless, zxcv were set in place where they are on qwerty.
Then I did some tweaking. I got a few lists of the most common digraphs (2 letter combinations) in english and used them to avoid typing them with the same finger without wrecking the frequency:comfort correlation too much. A lot of them are on different hands, and this is where this layout is weakest, as in my opinion they should be put on the same hand when possible just so long as it’s not with the same finger, as I think that’s the way typing flows best. So the opportunity to do that is lost, but I can deal with that.
So essentially I ended up with this:
with * being the spots that may gain priority if they’re found to be comfortable. Otherwise, they’ll be used for punctuation characters.