Scientists resurrected ELIZA, the world’s first chatbot

On December 21, 2024, around 2:00 p.m., scientists made the dead speak. ELIZA is the world’s first chatbot is coming back. Long imitated but not perfectly replicated, ELIZA was long thought lost. But scientists discovered an early version of the code in its creator’s archives in 2021 and spent the intervening years piecing it back together.

ELIZA has been revived and you can download from here to see for yourself.

Coded and replicated from 1964 to 1967, ELIZA was developed by MIT computer scientist Joseph Weizenbaum. Primitive by today’s standards, ELIZA was a hit when it was created. He gave her the persona of a psychotherapist, and her secretary was so enchanted that Weizenbaum asked her to leave the room while he talked to her.

A new scientific paper Members of the ELIZA Archeology Project tell us more about how they found and brought the chatbot to life, as well as its origins and subsequent distribution. Weizenbaum programmed ELIZA in an early language called MAD-SLIP on a time-sharing computer system called the Compatible Time Sharing System, or CTSS.

ELIZA quickly moved away from Weisenbaum. As it was originally distributed over computer networks, programmers adapted it to other languages. One of these early clones was built in Lisp by one of the technical leaders of ARPAnet, the precursor to the modern Internet. Eliza’s Lisp version was one of the first bits of data on this nascent network, and it spread quickly.

“As a result, Cosell’s Lisp ELIZA quickly became the dominant strain, and Weizenbaum’s version of MAD-SLIP, which did not appear on the ARPAnet, was consigned to history,” he said. “Until its rediscovery in 2021, the original MAD-SLIP ELIZA had not been seen for at least 50 years.”

Ten years later, a magazine called Creative Computing published an ELIZA clone written in BASIC. It was 1977 when the Apple II, Commodore Pet and TRS-80 hit the market. These machines led to an explosion in home computing and the spread of the BASIC computing language.

“And probably not enough hobbyists were interested enough in the possibility of writing artificial intelligence in this BASIC ELIZA (it was only a few pages of code) and experimenting with it themselves,” the scientists said. “Because of its brevity and simplicity and the personal computer explosion, this ELIZA has spawned hundreds of innovations in every imaginable programming language over the decades, making it perhaps the most hacked program in history/ Like Cosell’s Lisp ELIZA spread. BASIC ELIZA was spread through the ARPANet through a personal explosive infection of computers.”

There are countless versions of this BASIC version of ELIZA online today, and the original MAD-SLIP version was long considered obsolete. Later, Stanford computer scientist Jeff Srager convinced MIT archivists to dig through boxes of Weizenbaum’s material, and they made a critical discovery: early versions of the MAD-SLIP code.

The code was incomplete and it took a lot of fiddling and complicated emulation to get it working again. “This required cleaning and completing the code, installing and debugging the emulator stack, trivially fixing the found code itself, and even writing some completely new functions not found in the archives or existing MAD and SLIP implementations,” the paper noted.

It took time and a lot of effort, but code archaeologists have relaunched ELIZA and made it available for everyone to play with. “This has been tested on different versions of Linux and MacOS, but we’ve seen some issues with different versions, so your mileage may vary,” they said. “If you run it on your car and see something you need to change, let us know.”