AI-powered chatbots are clearly the future of computing, and it’s only a matter of time before you’ll see them appear on every internet-connected gadget. If you thought you were safe from this by sticking to an ancient MS-DOS PC though, think again: [Yeo Kheng Meng] has recently written a ChatGPT client that runs on DOS.

[Yeo Kheng Meng] didn’t cheat by simply running MS-DOS on a modern PC, either: he tested the client on a real 1984 vintage IBM 5155 Portable PC. This semi-portable PC/XT model sports a 4.77 MHz 8088 CPU, 640 kB of RAM and a CGA video card with a built-in monochrome monitor. An NE2000 ISA network card, running in 8-bit mode, enables the Portable to connect to the internet.

Running the client couldn’t be simpler: just run doschgpt.exe and type in your question. [Yeo Kheng Meng] developed this program using the Open Watcom C/C++ compiler, which was the compiler of choice for most DOS game developers back in the day. Networking support was provided by an era-appropriate packet driver together with MTCP, a TCP/IP stack developed by [Michael Brutman] for DOS-based internet applications.

Connecting to the ChatGPT API and parsing the results was pretty straightforward, but implementing the required TLS encryption was not. Even if there was a library available for MS-DOS, the 5155 wouldn’t have enough CPU power to run it in real time, so [Yeo Kheng Meng] decided to run that bit of the networking stack on a modern PC and send an unencrypted HTTP stream to the DOS client.

The end result is a delightful retro-futuristic setup that seems to have come straight out of a 1980s science fiction movie. We can already picture it together with a Commodore 64 reporting the news and an IRC server running on an IBM PC.