On December 21, 2024, just before 2 pm, scientists made the dead speak. ELIZA, the world’s first chatbot is back. Long imitated, but not perfectly replicated, ELIZA has long been thought lost. But scientists discovered an early version of its code in the archives of its creator in 2021 and have spent the intervening years piecing it back together.
ELIZA has been reanimated and you can download it here to see for yourself.
Coded and iterated from 1964 to 1967, ELIZA was developed by MIT computer scientist Joseph Weizenbaum. Rudimentary by today’s standards, ELIZA was a hit at the time of its creation. He gave it the personality of a psychotherapist and his secretary was so enchanted by it, that she asked Weizenbaum to leave the room when she chatted with it.
A new scientific paper from members of the ELIZA Archeology Project details how they found and resurrected the chatbot as well as its origins and subsequent dissemination. 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 got away from Weizenbaum. As it disseminated through early computer networks, programmers adapted it into other languages. One of these early clones was built in Lisp by one of the technical leads of ARPAnet, the precursor to the modern internet. The Lisp version of Eliza was one of the first bits of data on this nascent network and it spread fast.
“As a result, Cosell’s Lisp ELIZA rapidly became the dominant strain, and Weizenbaum’s MAD-SLIP version, invisible to the ARPAnet, was left to history,” the paper said. “Until it was rediscovered in 2021, the original MAD-SLIP ELIZA had not been seen by anyone for at least 50 years.”
A decade later, a magazine called Creative Computing published an ELIZA clone written in BASIC. It was 1977, the same year that the Apple II, Commodore Pet, and TRS-80 all hit the market. Those machines led to an explosion in home computing and the proliferation of the BASIC computing language.
“And probably not a small number of those hobbyists were interested enough by the possibility of AI to type in this BASIC ELIZA (which was only a couple of pages of code), and experiment with it themselves,” the scientists said. “Because of its brevity and simplicity, and the personal computer explosion, this ELIZA begat hundreds of knock-offs through the decades, in every conceivable programming language, making it perhaps the most knocked-off program in history/ Just as Cosell’s Lisp ELIZA spread via the ARPANet, the BASIC ELIZA spread via the explosive contagion of personal computers.”
There are countless versions of this BASIC version of ELIZA online right now and the original MAD-SLIP version was long thought lost to history. Then Stanford computer scientist Jeff Shrager convinced MIT archivists to root 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 tinkering and complicated emulation to get it running again. “It required numerous steps of code cleaning and completion, emulator stack installation and debugging, non-trivial debugging of the found code itself, and even writing some entirely new functions that were not found in the archives or in the available MAD and SLIP implementations,” the paper said.
It took time and a lot of effort, but the code archaeologists got ELIZA working again and they’ve made it available for anyone to play with. “This has been tested on various Linux and MacOS versions, but we’ve noticed some issues with different versions, so your mileage may vary,” they said in the paper. “If you get it working on your machine and find that you have to change something, let us know.”