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~Let's make 30-year-old pocket organiser Casio Business Navigator BN-20 run some new software, part 4~

Recap of the previous episodes: our friend gave us a pocket organiser. As it happens, the organiser is based on Intel 8086-compatible core. It is related to Casio Pocket Viewer series, but unlike the PV, it doesn't have a way to "side-load" the applications. 

So far we've dumped the ROM and tried to use it with Casio PV SDK. PV is compatible enough to kick-start the boot process, but the simulated OS crashes before it can even draw anything.

One interesting lead I decided to follow was the discrepancy between the CPU models in BN-20 and PV series: BN-20 runs on NC3020, and PV runs on NC3022. The documentation for Casio PV SDK mentions that a publicly-available simulator for NC3020 was a thing, too.

Can we find it? Can we run it? Yes we can! 
🧵

Two Stop Bits

A detailed reverse-engineering journey of a 30-year-old Casio Business Navigator BN-20 pocket organizer. The author successfully locates and runs the Casio Caleid SDK with its NC3020 CPU simulator (SIM3020), extracts ROM contents revealing the operating system structure, discovers extensive bitmap assets and built-in applications including handwriting recognition, kanji fonts, and games. The work involves navigating Japanese Windows 95, PC-98 hardware requirements, and DosBox-X configuration to achieve compatibility. All findings are archived for the community.

Nina Kalinina: "~Let's make 30-year-old pocket…"

<p>oh I love these. When I was a kid in the 80s/90s, I loved to check the latest calculators and mini computers with lcd screens. When I finally got one, it was a dream come true. I was able to create small programs on it with BASIC.</p>
