So a few years ago I found this beautiful and amazing website called cemetech.
And I noticed, that there was a Wiki for the PrizmSDK. At the beginning I was really frustrated because I couldn't find a download for it. But after changing the URL of a download link for the PrizmSDK 2.0 I found a website which listed all versions of the PrizmSDK. And I downloaded the latest SDK - PrizmSDK 3.0.
I have never used PrizmSDK before and I have never coded with c. I am familiar with Javascript, so I know the basics of coding. In the last days I made a test and-in. It was a Snake game. Everything works fine except when pressing menu. The Game quits to the Main menu (main function returns 0). But I can not launch it again. I found out that my game is not the only one having this problem. And also my game runs slow on older models of the Casio fc-cg calculators( I have FX-CG50) so I searched for an overclocking function (Ptune 2) and it works perfect but when launching Gravity Duck my calculator freezes. I know that Gravity Duck overclocks the device so I don't know which program causes the problem.
So I need help fixing those bugs. I use PRGM as key input and I know that GetKey works fine and could fix the bug but the function freezes the program and draws the status bar and that's not good for a game. So I have wondered if there is another way of fixing the bug. And also I noticed that VRAM doesn't work on the new Casio FX-CG50. How can I use the VRAM functions like drawing sprites or text?
Please Help. Thanks a lot.

The SDK versions are 0.2 and 0.3, not 2.0 and 3.0. The SDK never really got complete enough to warrant a 1.0 release...

Returning from the main function will always prevent you from re-launching the add-in without launching another add-in in between. As far as I know, there's no good solution other than using GetKey. But there's a clever trick that I think KermM's game Obliterate uses (I've only observed it through usage, not through studying the code): Use direct key input instead of GetKey, except when you detect that the the MENU button is pressed, immediately call GetKey. Assuming the user's press of the MENU button wasn't super short, this should make GetKey handle the return to the main menu immediately. But I haven't tested this myself, so I can't guarantee that what Obliterate is doing actually is the same as what I'm describing here!

If your game overclocks the calc, you should change back all the clock parameters once the user is done using your program. Also, if you're making a game that isn't just for your private use, I really would recommend making the overclocking optional, since not everyone wants to deal with the risks and the reduced battery life. It's unfortunate that Gravity Duck doesn't make its overclocking optional...

If VRAM access isn't working on the fx-CG50, the problem is probably that you're using the hardcoded address 0xA8000000 for the VRAM. Use the GetVRAMAddress syscall (http://prizm.cemetech.net/index.php/GetVRAMAddress) to obtain the address instead. Unfortunately, this syscall is not available in PrizmSDK 0.3 or earlier, and 0.3 is the latest release of the full SDK as of now. You can however download a newer version of libfxcg (which is a part of the SDK) and copy it into the SDK, and then you'll be able to use GetVRAMAddress.