The PC keyboard we use today, sucks big time. Let us count the ways.
PC keyboard we use is derived from the design of typewriters. The design of the typewriter itself, is largely concerned about getting the machine to actually work. Like most inventions, in the beginning the concern is just to get it to work. The concept of keyboarding ergonomics didn't come about or become popular after some 100 years.
Let's consider some examples:
The ⌫ Backspace key, the Return ↩ key, are among the most frequently used special keys. However, they are placed in the most inconvenient spots, pressed by the weakest finger the pinky.
Note that originally, on a typewriter of 1800s, these keys are not that frequently used. The Return ↩ is only pressed once about every 80 chars (per line), while ⌫ Backspace is rarely used or doesn't exist. But with computers, these keys are some of the most frequently used.
` 1 2 3 4 5 6 7 8 9 0 - =
Q W E R T Y U I O P [ ] \
A S D F G H J K L ; '
Z X C V B N M , . /
The vertical key column positions are jagged in irregularity. Look at 1 Q A Z. For the left hand, Going from key D to E, your middle finger moves upwards and in the direction of your pinky. But for right hand, going from K to I, your middle finger moves up in the direction of your thumb.
The number of keys for the left/right hands are not symmetric.
` 12345 67890 -=
qwert yuiop []\
asdfg hjkl; '
zxcvb nm,./
In the above diagram, notice how the right side has 5 extra keys, operated by your stretched pinky. Especially bad for programers because we need to type the [ ] { } = + often.
Ever wonder why the letters are arranged that way? Look at the top row of your keyboard, you see: Q W E R T Y …. It's arranged that way so that frequent letter combinations are hard to type fast so that the key hammers won't jam!
Solution: Dvorak Keyboard Layout
The Space bar, is huge, typically span 6 keys. It's a waste of efficient use of space. It's that way because it was a level on mechanical type writers, and the habit stuck.
Many modern keyboard now split the space into 2 or more keys. See: Tiny Space Bar on Japanese Keyboards
There are also issues of various hand angles, and hand separation.
and there's also wrist dorsiflexion, meaning bending up the palm. This happens when you use a thick keyboard that sits on a flat desk and your forearm rests on the desk surface. Especially bad when the keyboard's back legs are propped up. This is solved in several ways:
Many ergonomic keyboards are popular today, and they fixes all these issues. The most popular are the Kinesis Keyboard, Maltron Keyboard, Truly Ergonomic Keyboard. They fixed all of the above problems.
For many other ergonomic keyboards that fix these problems, see: Ergonomic Keyboards Gallery.
Alas, for most people, habit is a difficult beast to kill. You have to take about 2 months to get used to these new ways. Many programers, don't even touch-type, and insist that it works fine!