We could lay out a keyboard as a single row, thus
C C# D D# E F F# G G# A A# B C ...
but it would be rather wider than the current keyboard. The keys can't be made smaller because they have to fit human fingers. On a wide keyboard, it would be physically impossible to play certain chords. This will not do.
How about we add another dimension?
D F G# B D ...
C# E G A# C# ...
C D# F# A C ...
I've offset the rows slightly because it's hard to press two keys that are exactly aligned vertically. Also, it makes it easy to see that it is a progressive scale. This layout is somewhat similar to a computer keyboard.
Pianos only have one key for each note, because each key on the keyboard is fiddly and expensive. Electronic devices are cheap, so we can reasonably duplicate some keys:
c d# f# a c ...
D F G# B D ...
C# E G A# C# ...
C D# F# A C ...
d f g# b d ...
On this keyboard:
- It's trivial to transpose, just move your fingers to a new position. The two duplicate rows allow easy transposition of any music played on the middle three rows to any key.
- It's compact enough to play. In fact, it's more compact than a piano keyboard.
- Chords of the same type will all be the same shape. It's very much easier to see the link between the keys you press and the sound you produce (eg if a chord is minor or major).
Musical scores might be adapted to this notation also, for example here is a C major scale:
( ) B
--------------------------------------- A#
( ) A
G#
------------------------(-)------------ G
F#
( ) F
--------------(-)---------------------- E
D#
( ) D
--------------------------------------- C#
( ) C