Hollyhock Customization Tool

Hollyhock Customization Tool is a Windows Forms utility for modifying the Hollyhock firmware. It extracts RCDATA_3070 from the OS update DLL, lets you patch launcher menu text, version text and launcher filename (or supply a custom decompressed binary), recompresses the firmware and replaces the resource so the OSUpdate routine can flash it.

This project is distributed as source — you must compile it yourself.
I am not responsible if you brick your calculator. Use at your own risk, on legally owned hardware only.

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Quick facts

• Target device: fx-CP400 and fx-CG500.
• You must compile the project from source to produce HollyhockCustomizationTool.exe.
• Not responsible for bricked calculators, lost data, or legal issues.
• The tool expects several files(in bin/Debug) next to the compiled .exe:
  • OSupdateDLL_original.dll
  • fxASPI.dll
  • LanguageResource.dll
  • messages.txt

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Features

• Integrity checks (checksums) for required DLLs and messages file.
• Option to use a custom decompressed firmware binary or modify the embedded resource.
• Edit fields:
  • Launcher Menu Text (max 18 bytes)
  • Version Text (max 11 bytes)
  • Launcher File Name (max 7 bytes)
• Extract → verify → decompress → modify → recompress → replace resource → call OSUpdate.
• Operation log written to output.txt.
• Quick links to the project GitHub and Discord integrated into the UI.

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Build / Compile

1. Open the solution in Visual Studio.
2. Right-click on Form1.resx → Properties → enable “Unblock” in the bottom right
   This prevents resource loading errors during compile.
3. Go to Build → Build Solution.
   The executable HollyhockCustomizationTool.exe will appear in bin/Debug/.
4. Copy all required DLLs and messages.txt into the same folder as the .exe before running.

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Usage

1. Place the compiled HollyhockCustomizationTool.exe and the required files (listed above) into the same folder.
2. Run HollyhockCustomizationTool.exe. The program will verify checksums and exit if any file fails verification.
3. If you encounter issues:
   • It’s also possible that your antivirus or anti-cheat software could block the LoadLibrary and other functions, preventing the program from working correctly. You might need to temporarily disable them or whitelist the tool.
4. Toggle Use own firmware binary to:
   • Supply your own decompressed decompressed.bin via Browse.
5. Click Flash ROM to run the full routine. Monitor the on-screen output (and output.txt) for progress and errors.

Constraints are enforced (text byte limits). If you exceed limits the tool will refuse to proceed.

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Failure modes & logs

• All important steps append human-readable lines to output.txt. If something fails, paste the content of that file when asking for help.
• The tool currently lacks exhaustive exception handling in some internal calls — expect raw error messages in the output in edge cases.

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Legal / Liability / Safety (read this)

• You are fully responsible for the consequences of using this tool. I will not help recover damaged hardware caused by misuse.
• Use only on your own fx-CP400 or fx-CG500 with explicit permission. Do not use this to tamper with devices you don't own.
• This tool modifies firmware resources and invokes OS update routines.

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Links

• ClasspadDev: https://classpaddev.github.io
• Discord: https://discord.gg/knpcNJTzpd

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Short disclaimer (again)

Must compile yourself. Not responsible if the calculator is bricked. This is for the fx-CP400 and fx-CG500 only. Use with knowledge and care.