// HACKER NEWS — CYBERSECURITY
A True Telnet BBS on a Casio Calculator
About a eight weeks ago I had virtually no interest in calculators. Blank, dull, tedious-looking objects that remind me of long, arduous rainy afternoons in 1980’s/1990’s school maths classes.
Fast forward to August 14th, 2026 and I now own not one but two Casio Pocket Computer calculators (imported at great expense direct from Japan), have developed 4 pieces of software for them (one published to Github already, the rest will be open source for you to play with I promise!), made (AI generated) calculator fan art, and am now completely and utterly besotted with them.
It started quite simply with a post I read by Mark M5TEA on the SOTA Reflector. Mark had made mention that he had ported over a popular calculator emulator. Some sort of pocket Casio contraption that was able to write BASIC software as well as the C and Casio CASL languages.
I had a ‘curiosity click’ for the laugh, prodded a few buttons on the emulated calulator and thought little more of it. Later that day I went back for another look, curious to see how a calculator could run BASIC software, and moreto, how far could you push it?
Minutes turned to hours that turned to days. I was hooked. Starting out with the classic:
Before long I’d had my fill of testing random quick shot programs and began to think about what might be possible with the calculator thanks to it’s programability but also the hackability of it’s two gateways. A small interface port and a 2.5mm jack which masquerades as an RS232 serial input and output port.
This was the moment that hooked me. I began to think about one of my other passions, amateur radio – particularly CW (Morse Code). I don’t come from the world of software development and have very limited programming knowledge so I turned to an LLM to see could I vibe code a simple piece of software to log my radio contacts while operating portable.
This became the birth of my now published (and still very much alpha) Jamoncito FX logging software.
Shortly after I put together a small CW keying program, again written in BASIC. It’s unfinished and will require an external bridge circuit between the calculator and the radio to complete my goal, but it shows what can be done with a little thought.
Aside, I have long had a habit of keeping a pocket notebook and a fountain pen (your choice of stationary and writing implement may vary). If something pops in to my mind during the day (or night) I jot it down in case it’s of use another day. I also find it helps me declutter my brain, and in comparison to taking digital notes, it keeps me focused and the mix of random thoughts betwixt notes of genuine importance do not get lost in the digital void.