I once dismissed calculators as dull relics, but a post by Mark M5TEA on the SOTA Reflector sparked a change. I discovered a Casio VX‑4 emulator that could run BASIC, and curiosity turned into obsession. Testing simple programs—10 PRINT "HELLO WORLD"—showed the VX‑4’s quirky 8 kb RAM (expandable to 32 kb with an optional card, or even 64 kb on the FX‑870P) could handle more than expected.

The device also offers a 2.5 mm jack that masquerades as an RS‑232 serial port, opening possibilities for amateur radio interfacing. I built a basic CW keyer and a radio‑logging app, then set out to create a Bulletin Board Service hosted entirely on the calculator. Using an RS‑232‑to‑USB‑C FTDI cable and a Raspberry Pi Zero W as a silent bridge, the VX‑4 became a genuine telnet BBS, storing messages locally and archiving them to the Pi.

The project, now on GitHub, showcases the hidden potential of pocket calculators and inspires others to experiment with legacy hardware.