Jeff Shrager's repository introduces "executable archaeology" — the practice of recovering, transcribing, and running the original historical source of early computing programs so that the surviving artifact itself, rather than a modern rewrite, can serve as experimental evidence. The main project here is an IPL-V reimplementation of Victor Yngve's 1959–61 MIT sentence generator, run under Herbert A. Simon's account on 25 June 1962, whose surviving printout preserves the program, its phrase-structure grammar, execution traces, and handwritten corrections by Simon and his daughter Katherine.
- The repository also points to separate repos reconstructing the Logic Theorist in two historically distinct forms (LT1 in IPL-I and LT5 in IPL-V) and a full CTSS/IBM 7094 reanimation of Weizenbaum's original ELIZA
- A 2026 arXiv paper by Shrager and a 2025 IEEE Annals paper by Lane et al. provide the formal background
- Six stated principles govern the work, including distinguishing original behavior from behavior introduced by the reconstruction
- The repository also points to separate repos reconstructing the Logic Theorist in two historically distinct forms (LT1 in IPL-I and LT5 in IPL-V) and a full CTSS/IBM 7094 reanimation of Weizenbaum's original ELIZA
- A 2026 arXiv paper by Shrager and a 2025 IEEE Annals paper by Lane et al. provide the formal background
- Six stated principles govern the work, including distinguishing original behavior from behavior introduced by the reconstruction
Jeff Shrager writes a comprehensive guide to Herbert Simon's 1961 Heuristic Compiler, a program that uses General Problem Solver (GPS) means-end analysis to generate IPL-V code. After being dormant for roughly 65 years, the archival card deck was transcribed and successfully run on a modern Common Lisp interpreter. The system is composed of three parts: a State Description Compiler that derives code from before-and-after memory states, a Functional Description Compiler that modifies existing code based on imperative phrases, and a General Compiler executive that manages the search process. Notably, the program reproduces the exact machine code printed in Simon's 1963 paper, such as the "INSERT AT END OF VALUE LIST" and "SET SIGNAL MINUS" examples, without any modern language rewrites.
- The guide highlights that the compiler treats routine generation as a problem to be solved via operator search rather than a direct translation task.
- A debugging print statement left in routine U113 happens to output the exact stage-by-stage compilation sequence described in the 1963 paper.
- The original 1961 deck fails to compile the J3 routine; a specific card must be modified to erase a redundant description before the state compiler can execute successfully.
- The guide highlights that the compiler treats routine generation as a problem to be solved via operator search rather than a direct translation task.
- A debugging print statement left in routine U113 happens to output the exact stage-by-stage compilation sequence described in the 1963 paper.
- The original 1961 deck fails to compile the J3 routine; a specific card must be modified to erase a redundant description before the state compiler can execute successfully.
Paul Kimpel writes about a web-based emulator and operating environment designed for the IBM 1620 Model-2 computer system, which was a transistorized, decimal computing system from the 1960s. The project aims to provide a browser-based emulation of the Model 2 variant while recovering as much legacy software as possible.
- Features include support for memory sizes ranging from 20,000 to 60,000 digits.
- Includes an emulator written primarily in JavaScript and Scheme.
- The project documentation mentions various peripherals like the 1311 disk drive and 1443 line printer.
- Features include support for memory sizes ranging from 20,000 to 60,000 digits.
- Includes an emulator written primarily in JavaScript and Scheme.
- The project documentation mentions various peripherals like the 1311 disk drive and 1443 line printer.
This paper details the reconstruction and execution of the Logic Theorist (LT), considered the first artificial intelligence program, originally created in 1955-1956. The authors built a new IPL-V interpreter in Common Lisp and faithfully reanimated LT from code transcribed from a 1963 RAND technical report. The reanimated LT successfully proved 16 of 23 theorems from Principia Mathematica, consistent with the original system's behavior. This work demonstrates "executable archaeology" as a method for understanding early AI systems, highlighting the challenges and insights gained from reconstructing and running historical code.
- Raph Levien, who is an expert in Rust and rendering on GPUs, who founded Advogato, and who designed Inconsolata, a great monospace font. His talk's title is *I Want a Good Parallel Language*.
- Jeff Shrager will give a talk on reviving early AI programs like ELIZA and IPL-V. His talk's title is *RetroAI: Reanimating the Earliest AIs in the Lost Languages that Predated Lisp*.
- Jeff Shrager will give a talk on reviving early AI programs like ELIZA and IPL-V. His talk's title is *RetroAI: Reanimating the Earliest AIs in the Lost Languages that Predated Lisp*.
PDF of the second edition of Information Processing Language V Manual (1964).
This GitHub repository contains a re-implementation of the IPL-V programming language and the Logic Theorist (LT) program. It includes the original code transcribed into a TSV format and converted to Lisp, along with documentation and debugging tools.
The Wikipedia article details the Logic Theorist, created in 1956 by Allen Newell, Herbert A. Simon, and Cliff Shaw. Widely considered the first AI program, it successfully proved 38 of the first 52 theorems in Principia Mathematica, even discovering more elegant proofs than those originally crafted by Russell and Whitehead.
Jeff Shrager has reanimated LT in IPL-V with a new implementation.
