BDDNOW: A Parallel BDD Package. BDDs (binary decision diagrams) are ubiquitous in formal verification tools, and the time and memory used by the BDD package is frequently the constraint that prevents application of formal verification. Accordingly, several researchers have investigated using parallel processing for BDDs. In this paper, we present a parallel BDD package with several novel features. The parallelization scheme strives for minimal communication overhead, so we are able to demonstrate speed-up even running on networked commodity PC workstations. Average memory utilization per node is comparable to that of efficient sequential packages. In addition, the package supports dynamic variable reordering, and simultaneous computation of multiple BDD operations. Finally, the package is designed for portability - providing a subset of the CUDD API for the application programmer, and running on the widely available PVM package.