[exayhpao] Keyboard arrangements

Let "finger" be shorthand for the 4 fingers excluding the thumb.

3 rows of 4 buttons for the 4 fingers = 12.  1 button for thumb = 13.  2 hands = 26 which is the number of letters in the alphabet.  More thumb buttons for space, punctuation, etc.

5 buttons for the thumb.  2 hands = 10 which is the number of digits 0 through 9.  Maybe 6 buttons adding backspace and escape.  Perhaps for smartphone soft keyboard.

2 rows of 4 buttons for 4 fingers = 8.  2 hands = 16 for hexadecimal input.