Pilot (operating system)

Pilot was a single-user, multitasking operating system designed by Xerox PARC in early 1977. Pilot was written in the Mesa programming language, totalling about 24,000 lines of code. Pilot was designed as a single user system in a highly networked environment of other Pilot systems, with interfaces designed for inter-process communication (IPC) across the network via the Pilot stream interface. Pilot combined virtual memory and file storage into one subsystem, and used the manager/kernel architecture for managing the system and its resources. Its designers considered a non-preemptive multitasking model, but later chose a preemptive system based on monitors. Pilot was used as the operating system for the Xerox Star workstation.