Turbo Pascal 3.02A, deconstructed

Simon Willison’s Weblog Subscribe Sponsored by: WorkOS — The infrastructure fast-growing B2B companies use to sell to Enterprise. Turbo Pascal 3.02A, deconstructed. In Things That Turbo Pascal is Smaller Than James Hague lists things (from 2011) that are larger in size than Borland's 1985 Turbo Pascal 3.02 executable - a 39,731 byte file that somehow included a full text editor IDE and Pascal compiler. This inspired me to track down a copy of that executable (available as freeware since 2000) and see if Claude could interpret the binary and decompile it for me. It did a great job, so I had it create this interactive artifact illustrating the result. Here's the sequence of prompts I used (in regular claude.ai chat, not Claude Code): Read this https://prog21.dadgum.com/116.html Now find a copy of that binary online Explore this (I attached the zip file) Build an artifact - no react - that embeds the full turbo.com binary and displays it in a way that helps understand it - broke into labeled segments for different parts of the application, decompiled to visible source code (I guess assembly?) and with that assembly then reconstructed into readable code with extensive annotations Posted 20th March 2026 at 11:59 pm Recent articles Thoughts on OpenAI acquiring Astral and uv/ruff/ty - 19th March 2026 GPT-5.4 mini and GPT-5.4 nano, which can describe 76,000 photos for $52 - 17th March 2026 My fireside chat about agentic engineering at the Pragmatic Summit - 14th March 2026 This is a link post by Simon Willison, posted on 20th March 2026. computer-history 16 tools 52 ai 1921 generative-ai 1703 llms 1669 claude 262 Monthly briefing Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments. Pay me to send you less! Sponsor & subscribe Disclosures Colophon © 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026