Xah Lee, 2008-07-10
Swapping the Caps Lock key with the Control key is one of the bad advice in keyboarding. It's one of the myth that perpetuate bad practice.
Here are the good tips:
Among tech geeking circles, it's widely recommended like a dogma, to swap Caps Lock and Ctrl keys. However, remapping Control to Caps Lock seriously violates some basic ergonomic principles.
In touch typing, modifiers comes in pairs, such as Shift. The accepted ergonomic way to press them is using one hand to press the modifier and the other to press the letter key.
You can see how it is otherwise by disabling one of the Shift key. With just one modifier, you are heavily handicapped. As a example, try this exercise:
TYPE THIS SENTENCE WITH JUST ONE SHIFT KEY AND WITHOUT USING CAPS LOCK.
Quickly, you'll see the pain.
Similar is with other modifier keys such as Alt and Ctrl. The reason they are not noticed only because they are seldomly used. However, in emacs, it is heavily used. So, by mapping Ctrl to the Caps Lock key, you put a severe handicap by putting all work into the left pinky, and restrict the number of keys you can comfortably use with Ctrl.
The reason that many tech geekers still recommend it is because the Ctrl key is traditionally on the corner of keyboard and rather difficult to press. Also, many keyboards does not have right Ctrl. So, in a sense, Caps Lock as Ctrl is a improvement. It is especially a good solution on labtop keyboards.
There are 2 ways to remedy the problem of pressing of Ctrl.
One is to buy a good keyboard that has big Alt and Ctrl keys, and on both sides of the keyboard, and symmetrically placed with respect to your thumbs when hands in home position. (some keyboards, such as Apple's, has the right side modifiers far to the right, rendering them unusable for touch typing) Microsoft's ergonomic keyboard satisfies this requirement (MS's ergo keyboards is quite popular, and in fact MS's input devices is highly received. I haven't checked the facts, but i think MS's input devices has the largest market share. The second now is perhaps Logitech.).
The other way is to learn to type the corner Ctrl by pressing down your palm or semi fist, instead of poking it with your pinky. This can be easily done on most PC keyboards.
To see which is better, you can type this sentence and press Ctrl for every letter. (do it outside of emacs) You can quickly find out which way is better for you.
The above assumes you touch type. If you don't, some tips may not apply.
Joel wrote: «... do not use two fingers on the same hand at the same time, except in emergencies. ...».
YSK wrote: «Seriously? I do this all the time. Some of my favorite (non-emacs) shortcuts include stuff like C-M-S-e, all done with my left hand. Is that bad?».
yes and no. In general, if you just have one modifier key and one letter key, the proper touch typing guidline is to use one hand on the modifier and the other on the letter. Choose the modifier on the other side of the letter key.
You can test this out.
Try to type this whole sentence in captical letters (but without using Caps Lock).
First, try it using just the left Shift key. Then try it using the touch type guidline as above. You'll see how using single hand creates pain. Similarly, you can try the above with the Control key as modifier.
When you have multiple modifier, it gets a bit more complex and the rule applies less. Ultimately, there are several factors involved. For example, the keyboard hardware is not well designed due to historical reasons. Secondly, many keyboards such as Apple's that has the right hand side's modifier far to the right, making them less usable for touch type. Lastly, the principles of ergonomics presumes you are doing the task repeatitively for a prolonged time. Else it doesn't apply. For example, for vast majority of computer users (say 95%), they only type maybe for 1 hour per day, and there's not much activity of continued typing more than 5 min. Lots of professional programers don't even touch type; partly because heavy duty data-entry is not really part of programing.
And when it comes to Control key, or multiple modifiers, they are not used that much often, so whichever works for you is ok. However, this does not mean it's completely a personal issue without any scientific criterion on which is considered better. For example, of all the styles and anecdotes you hear about how you should press modifier, you can easily test them out and find the better one, by say, force yourself to continuously operate it for 10 min using one way, then do the same test with another way. You'll quickly see which one is more tiring and which is faster with less effort.
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