Akhil Nadh PC. ChorusOS is a real-time microkernel operating system designed as a message-based computing model. ChorusOS started as a distributed real-time operating system Chorus, Mach Case Study Distributed System. Mach runs on multiprocessor and uniprocessor computers connected by networks. It was designed to enable the evolution of new distributed systems while maintaining UNIX compatibility. Mach's is a flagship design. He integrates. especially. sophisticated interprocess communication and, 3. HISTORY of Unix 2 • AT amp T, owner of Bell Labs, distributes UNIX to universities for a nominal fee. • The University of California at Berkeley transfers UNIX to the VAX 4BSD and implements virtualization. Representing a revised and significantly expanded Part II of the best-selling modern operating systems, it covers the material of the original book, including communication, synchronization, processes and file systems and adds new material on distributed shared memory , real-time distributed systems, fault-tolerant distributed systems. Case studies explore popular operating systems and provide real-world context. Tanenbaum also provides information on current research, based on his experience as an operating systems researcher. The th edition keeps pace with modern operating systems with a new chapter on new security coverage, a focus on Flash-based SSDs,