The Sharp PC-G801 was an impressive little pocket computer when it debuted in 1988. However, in the year 2025, a Z80-compatible machine with just 8 kB of RAM is hardly much to get excited about. [shiura] decided to take one of these old machines and upgrade it into something more modern and useful.
The build maintains the best parts of the Sharp design — namely, the case and the keypad. The original circuit board has been entirely ripped out, and a custom PCB was designed to interface with the membrane keypad and host the new internals. [shiura] landed on the Raspberry Pi Zero 2W to run the show. It’s a capable machine that runs Linux rather well and has wireless connectivity out of the box. It’s paired with an ESP32-S3 microcontroller that handles interfacing all the various parts of the original Sharp hardware. It also handles the connection to the 256×64 OLED display. The new setup can run in ESP32-only mode, where it acts as a classic RPN-style calculator. Alternatively, the Pi Zero can be powered up for a full-fat computing experience.
I used my N900 as a daily driver for a few months in 2020, but it was a constant pain and the www is right out anyhow. Never tried the Droid 4 (though I did order one, but then gave it away) and Maemo leste was not ready for prime in 2020 on any device, but I believe they're much better now. I believe the Droid 4 was top tier back in 2012.
Having that keyboard is not that big of a priority for me; I'm not likely to spontaneously start hacking while out and about; I can tweak my phone from the comfort of a real keyboard and an ssh connection.