Reverse-Engineered geoWrite 2.1 for C64 Source Code

geoWrite is a WYSIWYG rich text editor for the Commodore 64 GEOS operating system. I created a reverse-engineered source version of the geoWrite 2.1 for the C64 (English and German) for the cc65 compiler suite:

The source compiles into the exact same binaries as the English and German versions of geoWrite 2.1 included with GEOS 2.0.

Not all code has been commented yet, contributions are welcome.

The article series on geoWrite internals is based on the results of this reverse-engineering effort. Here is the list of articles in the series again:

  1. The Overlay System
  2. Screen Recovery
  3. Font Management
  4. Zero Page
  5. Copy Protection
  6. Localization
  7. File Format and Pagination
  8. Copy & Paste
  9. Keyboard Handling

3 thoughts on “Reverse-Engineered geoWrite 2.1 for C64 Source Code”

  1. I have this complex idea that copies another. When Freethegameboy ported NES (3.84 Mhz) to the 48Mhz Apollo3, they ported an emulator from the STM32F746 to the CortexM4 Ambiq: “Specifically, we have used Game Boy emulator for STM32F746 Discovery board written by Uwe Becker.”

    So, this same technique could be used to port the C64 emulator built for a related CortexM4 family, the STM32F4, by Staringlizard, to the Apollo3 or 4: This way, you could develop a solar powered C64 emulator with GEOS into a laptop, like a lightweight Psion 3, but with WIMP and use a low power display: (eink too)


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