Skip to content

Introduction

HollyHock3, the successor of Hollyhock2, operates as a custom mod for ClassPad calculators. To make HHK work, you need to install it on your calculator. If you have not done this yet, go to our Install HollyHock3 MOD page to learn how to do it.

If you just want to run apps, go to the ClassPadDev store. If you want to create simple programs and games, start with Python and try the rectangle example. If you want to create a very fast game, consider gint. The HH3 SDK is for developers who want to run apps inside the ClassPad OS and want good C++ tooling.

This section of the wiki is about the HH3 SDK, the successor of the HH2 SDK. It keeps similar libraries and the same ease of portability, so most of your old knowledge still applies. It is a good choice when you want to play nicely with the Casio OS, use newer C++ features, and try experimental features. It is also the easiest way to start, because most of the wiki docs are written for it. It is not always the best choice: if you want the best performance for games, the gint kernel talks to the hardware directly and is usually faster.

V3 Templates

Section titled “V3 Templates”

For those wanting to try the new V3 beta, the easiest way to start is by setting up a Github Codespace. You’ll get coding instantly without the need to download or configure anything on your computer.

We currently have two template options:

📱 HHK3 Basic Template Basic template for HollyHock-3 development without additional libraries
🎨 HHK3 UI Template Template with uGFX library for advanced UI development in HollyHock-3

If GitHub prompts for login, you’ll need to create a GitHub account to use Codespaces. Don’t worry, it’s a quick and free process! Plus, enjoy 120 hours of free usage per month, more than enough to dive into coding, create cool apps, and kickstart your development journey.

For advanced users, alternative methods are available, but for beginners, we highly recommend starting with Codespaces for the quickest and user-friendly experience. Dive into coding effortlessly and build your projects with confidence by taking a look at the tutorial.

Understanding the Changes

Section titled “Understanding the Changes”

To better understand what’s changed in V3, you can compare the CPDoom migration:

CPDoom V3 Migration Compare the V3 version of CPDoom with the original V2 version to see the differences
CPDoom V2 Original Original V2 version of CPDoom for comparison with V3 changes

Advanced Development Setup

Section titled “Advanced Development Setup”

Most people should start with one of the templates above. But if you want your own development environment, or you want to set up CI/CD, the reference setup is the devcontainer of the HHK3 template. Its Dockerfile uses ghcr.io/classpaddev/hollyhock-3:v2.2.2 as the toolchain stage, then copies /toolchain (the compiler) and /sdk (the prebuilt SDK) into a Debian 13 base. On top of that it adds make, git, mold, clangd-19 and bear.

FROM ghcr.io/classpaddev/hollyhock-3:v2.2.2 AS toolchain

Windows

Section titled “Windows”

Install Docker Desktop (with WSL2) and VSCode with the “Dev Containers” extension. Open the HHK3template folder in VSCode. When VSCode asks to “Reopen in Container”, accept it. You now get a ready terminal with the compiler at /toolchain.

Linux

Section titled “Linux”

The same works with Docker Desktop, but the lightest path is podman with VSCode. Install podman and podman-compose (or use the docker-mirror from the podman-docker package). Then install the Dev Containers extension and set it to use podman. On Arch Linux this is what the maintainers use day to day.

You can also pull the image directly with docker pull ghcr.io/classpaddev/hollyhock-3:v2.2.2. With podman the same command works. Or you can build it yourself from the Dockerfile in the template repository.

Section titled “Recommended VSCode extensions”

These come from the template’s devcontainer config:

  • ms-vscode.makefile-tools: Makefile support.
  • ms-vscode.cpptools and ms-vscode.cpptools-themes: C and C++ support, plus color themes.
  • llvm-vs-code-extensions.vscode-clangd: code intelligence. The template already sets it up with the right cross-compiler driver.
  • xaver.clang-format: code formatting.
  • ZixuanWang.linkerscript: linker script highlighting.
  • ms-azuretools.vscode-docker: Docker integration.

CI/CD

Section titled “CI/CD”

For automated builds, look at the GitHub Actions of the HHK3 template, which is a working example: HHK3template actions. It builds the project on every push and pull request using the same toolchain image.