Abstract. We consider the dynamics of a single shock in a Partially Asymmetric Simple Exclusion Process (PASEP) on a finite lattice with open boundaries in sublattice-parallel updating scheme. We then construct the steady-state of the system by considering a linear superposition of these shocks. It is shown that this steadystate can be also written in terms of a product of four non-commuting matrices. One of the main results obtained here is that these matrices have exactly the same generic structure of the matrices first introduced in [7] indicating that the steady-state of a onedimensional driven-diffusive system can be written as a linear superposition of product shock measures. It is easy now to explain the two-dimensional matrix representation of the PASEP with parallel dynamics introduced in [8,9].