MULTICS

Multics, short for Multiplexed Information and Computing Service, was an influential time-sharing operating system developed in the 1960s as a joint project of the Massachusetts Institute of Technology (MIT), General Electric, and later Honeywell. It was designed to provide extensive online computing resources with high reliability, security, and flexibility, suitable for a research community and business environments.

The project originated at MIT's Project MAC in 1964, with support from ARPA, and used hardware provided by GE (notably the GE‑645 mainframe) and later continued by Honeywell after GE withdrew. The system underwent several releases from the late 1960s through the 1970s. Although never deployed as a mass-market product, Multics influenced many later systems through its emphasis on robust concepts and architectural ideas.

Key technical features included a hierarchical file system with built-in security controls, a multi-layer protection architecture intended to isolate software components, dynamic linking of modules at runtime, and strong support for time-sharing and multitasking. The system was designed for modularity and online maintenance, with comprehensive access controls and a focus on reliability and fault tolerance.

Multics had a lasting impact on the design of operating systems. Its ideas shaped research and production systems and contributed to a culture of security‑centric OS design. Concepts such as hierarchical file organization, robust protection mechanisms, and modular software design influenced later systems, including the development of Unix and other successors, which in turn helped shape modern operating system practice.