ELIZA Reanimated: Restoring the Mother of All Chatbots to One of the World’s First Time-Sharing Systems

ELIZA, created by Joseph Weizenbaum at MIT in the early 1960s, is considered the earliest chatbot. He programmed it in Michigan Algorithm Decoder-Symmetric List Processor (MAD-SLIP) on MIT’s Compatible Time-Sharing System (CTSS) operating system, on an IBM 7094. We discovered an original ELIZA printout in Prof. Weizenbaum’s papers at MIT’s Institute Archives, including an early version of its famous DOCTOR script, a nearly complete version of the MAD-SLIP code, and various support functions in MAD and Fortran Assembly Program. Here we describe the reconstruction and reanimation of this original ELIZA on a restored CTSS, running on an emulated IBM 7094. The entire stack is open source, so that any user of a Unix-like operating system can run the world’s earliest chatbot on their own version of a pioneering time-sharing system.