We propose a novel memory sharing scheme ``Asymmetric Distributed Shared Memory: ADSM'', that realize user-level protected high-speed high-functional communications/synchronizations. The ADSM scheme is developed for the general-purpose massively-parallel operating system: SSS-CORE on Network of Workstations (NOW) or distibuted-memory multiprocessors. We describe two programming models and two execution models suitable for ADSM on the SSS-CORE. We also introduce Memory-Based Communication Facilities of the SSS-CORE which enable a high-speed imprementation of ADSM. Next, we describe the implementation status of the current SSS-CORE on NOW. Finally, we show actual measurements of exection times and communication overheads in fine-grained applications on the SSS-CORE.