What is Prizmchess?

Prizmchess is a chessboard for the Casio fx-CG50 Prizm calculator. It is written in C++ and uses the libfxcg library to control the calculator’s hardware. It is (planned to be) fully-featured, including a simple chess engine, PGN game storage, a chess clock and more. It is currently in early development.

How do I use it?

We haven’t actually even begun to develop the app, and it is still just a plan. In the future, however, you can download the source code from GitHub and compile it yourself. Check the README for more information.

Alternatively, you can download the latest built version from the releases page.

Technical Details

Prizmchess is written in C++ and uses the libfxcg library for the calculator’s hardware. The C++ code is compiled to a .bin file that is then packaged in a .g3a file by the mkg3a tool.

The app is currently paused until after me and Harik finish our GCSEs, so I can’t really comment further on the architecture. You can view the development progress on my GitHub project board.

Blog

After I finished the initial release of my KChess project, my friend Harik was reminded that he had been in a very similar situation, as the only chess app for the Prizm was created for the earlier fx-CG10 and fx-CG20 calculators. These calculators have a black screen, so the chessboard was displayed in white, but the fx-CG50 Prizm has a white screen, so the chessboard (still in white) was invisible.

At first, we thought that we could just change the colour of the chessboard, but we soon realised that the existing chess app was completely written in Hungarian, and we didn’t want to translate all the code and comments for fear of messing with something we didn’t understand. So we eventually decided to start from scratch.

Finally, I had never used C++ before and Harik was quite experienced with it, but I had made my own chessboard before, so we decided to work on it together.

The first step to developing the app was to set up the development toolchain. This already created a problem for Harik, as he was using Windows, and the provided make.bat file on the SDK did not seem to work. I was using Linux, and so I was able to use the make command to compile the app. After testing the hello world app on Harik’s calculator (as I don’t have one), we moved on to actually developing the app.

The next challenge was to solve many of the issues that I managed to skirt around in my KChess project. The first of these was the staggering (from my perspective) amount of memory that the Prizm has. The Prizm has 64KB of available RAM, which is far less than the 512MB available on the Kindle and the comparatively massive gigabytes available on my computer. This meant that I had to be very careful about how I used memory, which was a unique challenge I had never run into before. We had to plan out all the data structures that we would need, and make sure that we didn’t use more than we needed to (as a contrast to the individual JPanel chess squares in KChess).

We did some initial planning for the next phase of the project, as you can see on the project board, but after some consideration Harik decided that he wanted to instead focus on the upcoming GCSEs, so the project is paused until after then.