  The first version of the Binary Population Synthesizer (BiPoS1) is made
publicly available. It allows to efficiently calculate binary distribution
functions after the dynamical processing of a realistic population of binary
stars during the first few Myr in the hosting embedded star cluster. Instead of
time-consuming N-body simulations, BiPoS1 uses a stellar dynamical operator
which determines the fraction of surviving binaries depending on the binding
energy of the binaries. The stellar dynamical operator depends on the initial
star cluster density as well as the time until the residual gas of the star
cluster is expelled. BiPoS1 has also a galactic-field mode, in order to
synthesize the stellar population of a whole galaxy. At the time of gas
expulsion, the dynamical processing of the binary population is assumed to
efficiently end due to the subsequent expansion of the star cluster. While
BiPoS1 $has been used previously unpublished, here we demonstrate its use in
the modelling of the binary populations in the Orion Nebula Cluster, in OB
associations and as an input for simulations of globular clusters.
