Saturday, February 9, 2013

Back At It

Hey...anyone still there?  Oh, yeah?  Awesome...

CoCo Coding Contest

There is a coding contest in progress for CoCo enthusiasts, with the winner to be picked at this year's CoCoFEST! in Chicagoland.  You know that I can't sit that out!  But what to do?

After a little thought, I decided to use my 44-color display mode as the basis for a sliding puzzle game.  I doubt if that will be the most amazing CoCo game ever, but at least it should earn me a ribbon for participation... :-)

Prep and Clean-up

I left the code for this project a bit undone last Summer.  It would load in my local environment, where I use a monitor program over a serial port.  But it wouldn't load under a normal Color BASIC-based environment on the CoCo or Dragon.  I took a little time today to relocate the code and generate the necessary images for loading the code in such an environment.

Want to PAL around?

The code for my 44-color display mode counts display lines in order to coordinate VDG register changes with which lines are currently being displayed.  This counting requires the code to know how many lines are displayed in each frame, and that number is different between NTSC and PAL video modes.  I only have NTSC CoCo machines, including my Tano Dragon.  So, I don't have any way to test PAL-aware code.

If you are using PAL hardware and you are interested in seeing my 44-color mode in action, then maybe you can help me?  It should be as easy as increasing the number of non-displayed lines to count, but that number might need to be tweaked a bit depending upon exact cycle counts and such.  If you want to help me figure that out, then let me know!

For everyone else, watch this space while I roll-out my 44-color sliding puzzle game!


  1. Someone asked about the Brazilian PAL machines. Brazil had a wierd video standard that took the timing from NTSC and combined it with the color signals from PAL.

    My guess is that those machines (e.g. the CP-400) will probably work with the NTSC code. I have a CP-400, but I'm not in a position to test it immediately. Maybe the active Brazilian CoCo folks will give it a try too?

    Someone asked if this code worked with the emulators. The xroar emulator (in NTSC mode) seems to more-or-less work. It throws a glitch in the video every few seconds, but the overall effect is clearly observable. If its PAL mode is roughly as accurate as its NTSC mode, then that might be sufficient for me to develop a PAL version just with that...