A True Telnet BBS on a Casio Calculator
A developer fell in love with Casio pocket computers after discovering their BASIC and RS232 capabilities. He built a fully functional telnet BBS hosted entirely on a Casio VX-4 with just 8KB of RAM, using a Raspberry Pi Zero W only as a network bridge and message archive. The BBS, written in BASIC, accepts calls via telnet and prompts for a callsign. The project is still in development, with plans to publish the code on GitHub.
How about a Bulletin Board Service? How original you might say. Yes, but how about a BBS hosted entirely on a calculator with 8kb of RAM?