The earliest known keyboards date from before 1000 A.D. and were attached to church organs. The keys were as far apart as the organ's pipes and were played with the fists or even the knees.and
Cristofori had solved most of the practical problems of the hammer mechanism, but his instrument caught on slowly. Though they both had tried out the pianoforte, neither Johann Sebastian Bach nor Georg Frideric Handel composed for it..True enough. But it does seem that Bach was fairly interested in the development of the instrument, and was helpful in selling some of the subsequent fortepianos made by Silberman.
If you're curious, there's a very interesting and worthwhile account of Bach's keyboards:
Herr Bach plays not only a quite slow, singing adagio with the most touching expression... he also sustains in such a slow movement a note of the duration of six semiquavers with all the varying degrees of loudness and softness, and this in the bass as well as in the treble.Link.
You can hear some of Bach's music played on clavichord, the Silbermann fortepiano, and harpsichord here.