Operating Systems – Foundations of Modern Computing - CTSS Operating System

The Compatible Time-Sharing System (CTSS) and IBM 7090 Legacy The Compatible Time-Sharing System (CTSS) was a groundbreaking 1960s operating system developed at MIT that pioneered the ability for multiple users to interact with a computer simultaneously. Running on modified IBM 7090 and 7094 mainframes, it introduced essential modern computing concepts such as password-protected logins, electronic mail, and instant messaging. The system was notable for its "compatibility," allowing interactive tasks to function alongside traditional batch processing. In addition to hosting early innovations like the ELIZA chatbot and specialized tools for braille translation, CTSS served as the direct predecessor to Multics and eventually influenced the creation of Unix. Modern enthusiasts continue to preserve this legacy through software simulators and reconstructed source code that allow the system to run on contemporary hardware.