  We consider the master/slave parameterised reachability problem for networks
of pushdown systems, where communication is via a global store using only
non-atomic reads and writes. We show that the control-state reachability
problem is decidable. As part of the result, we provide a constructive
extension of a theorem by Ehrenfeucht and Rozenberg to produce an NFA
equivalent to certain kinds of CFG. Finally, we show that the non-parameterised
version is undecidable.
