Introduction to Distributed Systems: Distributed systems: Goals Hardware Concepts Software - design ,Communication distributed systems: Layered Protocol: ATM Networks client server model - remote procedure call – group communication. Synchronization: Clock synchronization - mutual exclusion - election atomic transactions - dead locks. Process and Processors: Threads - System models processor allocation - scheduling fault tolerance - real time distributed systems. Distributed file systems: File system design and implementation - trends in distributed file systems. Shared Memory: Introduction - bus based multi processors ring based multiprocessors switched multiprocessors - NUMA comparison of shared memory systems - consistency models - page based distributed shared memory - shared variable distributed shared memory - object based distributed shared memory. Case studies: MACH and CHORUS