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A Modern Reincarination of Graphire: WACOM Bamboo Series Drawing Tablet Reverse Engineering

This is going to be a short follow-up of the previous article; please read that one before proceeding:   https://www.lithcore.cn/2024/02/wacom-et-0405-reverse-engineering.html . Same as before, all the high-resolution PCB scans have been uploaded to GDrive:  https://drive.google.com/drive/folders/1vGHHMH9WkavLYoCPT2HWrooUTZOjV1wc I'm personally attached to the Bamboo product line because that is where I got started 10 years ago. The Bamboo product line is initially made of cheap pen-tablet products designed for the entry-level market. WACOM intentionally limited the performance of those products to avoid direct competition with their professional Intuos product line.  Interestingly, by the time I started using their products, WACOM had gradually shifted the focus of this product line to experimental and high-diversity products, including mobile phone styluses, ultrasonic pens (The first Bamboo Inkling product), mobile phone applications, and paper-based products (e.g. Bamboo Folio

Hacking a CASIO fx-5800p Programmable Calculator

 Some information about the internals of fx-5800p, a cute programmable calculator that was very popular in the surveying market in China in the past.

1. SoC

Dieshot

  • SoC Markings: OKI ML610901B (CPU, RAM, Mask ROM, LCD Driver)
  • Flash: 29LV800CBT (Only half of the Flash ROM is being used)
  • RAM: 62256
  • Oscillator: Unknown, probably embedded.
  • The oscillation frequency can deviate by quite a lot during serial communication. It's probably an RC or on-chip RC oscillator.

2. OS Update & Data Encoding

“OS” refers to the binary data residing in the external Flash ROM. In fact, most of the core math, hardware access, communication, and maintenance functions are hard-wired inside the SOC (Mask-ROM). The font set and the power-off screen are also in the Mask-ROM.
From what I know so far, the UI, statistics, and programming functions are probably in the external flash, which can be reprogrammed.
To enter the OS Update menu:

  1. Shutdown the device using [SHIFT]+[AC/ON]
  1. Hold [MODE]+[7], Press [AC/ON]
  1. Press [⬅️], then [9]
You’re now in the maintenance menu, press [2] for OS Update functions. (Warning: you may accidentally delete your OS, be careful. Self-test or OS Update will cause a memory clear)


OS Update Process

Notice the data transmission is scrambled. It's probably some early form of bitstuffing.

3. et cetera

Some photos



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