Galactica Net employs a unique approach to supporting shared memory coherence in a distributed computing system. The approach is based upon the use of operating system software for the complex management of sharing information, but provides hardware support for the most important coherence operations. The goal is to delegate as much of the complexity to software as possible, while still exploiting hardware to ensure high performance. In this paper , we describe the Galactica Net update-based coherence protocol and the hardware required to implement that protocol. We also present basic performance data obtained through detailed hardware simulations.