I found out about hardware scrolling on the z80 calcs a while ago. I did some experimentation and this is the result. It is incredibly fast. The main loop has a Pause 200 in it. It just rotates the screen now but in the future new rows will be placed at the edge of the screen. Scrolling and the cursor work now.

Edit: Added poll

I will be working on a lightweight chiptune player interrupt routine. You can just slap that on a game and have instant music (given you have a soundchip plugged in). How bout that?

This program will take the raw data from any kind of file and put it in an appvar. The extention does not matter. If you have a power point presentation under 64k you want to convert to an appvar you can do that It will just copy all the bytes. The only thing my program does is generate the headers for the appvar and write it all to a new file.

To input .db $FF you get a hex editor and make a new file with $FF in it. Just one byte. Open the command prompt and change directory. Now run my program like this:
to8xv yourfile.ext appvar.8xv TESTVAR

Now try to send appvar.8xv to your calculator to test it

Allright I had to scrap some things in order to make it work, but now we're golden (hopefully)
I am polling the SPI registers in order to receive bytes with the arduino. This is because the interrupt driven method was not ideal in this situation. Bytes would get lost because the SID emulator's timer interrupt was blocking the SPI interrupt.

As long as there is enough delay in between writes it's fine. I imagine you could use interrupts on the calculator to send one byte at a time and still have plenty of cycles left for your program.

I also wrote a PC program that allows you to convert any data to an appvar. I used it to convert SID dump files to appvars. I successfully played one back. I need some kind of compression though cause those dump files are huge.

Edit: The sawtooth wave of the emulator sounds terrible, so I am probably going to have to rewrite some of the emulator's code. I hope I will be able to pull that off without breaking something in the process I am taking out my scope to try to find out what is wrong with it.

Just drag-and-drop *.8xp files onto this executable, and it will convert them to *.8xv files.

*Bump* That .exe is not compatible with windows 7 32 bit. Is there a 32 bits version?

Wow even mode7 graphics. I own a physical copy of this game. I only played it for an hour and then put it away because I had to leave for school. I should give it another shot.

Working on this again
I use hardware SPI for the data transfer now! It is super fast! It is unidirectional though. I2C would be bidirectional, but it is a bit harder to set up. I might change it to I2C some day.

Edit: I got it working and it is much faster, cleaner and more reliable than ever before!

How much of it goes to the community?