The early version of the prelude (ca.1738) is found in Go.S.19
only. It explores less expressive potential 
.
There are two further preludes which may be mentioned here: they were previously paired with the early version of the accompanying fugue (BWV 902/2).
- BWV 902a (ca.1720): the earlier one transmitted to Kellner's
MS P 804 alone. Written in 3/4 metre in 33 bars, this is a
closer match to BWV 902/2 both motifically and stylistically .
- BWV 902/1 (ca.1730): the later one commonly found in the early
sources such as P 1089, replacing BWV 902a. It is a substantial
binary piece (in quasi-sonata form). Stylistically it is more mature (4/4
metre in 56 bars with repeats) than the version found in P 804 .
There is a slightly revised version reflected in N.Mus.ms.10490.