Awesome work, your avr computer is really impressive! So similar and yet so different! Emulating the Apple II was relatively easy, not a lot of extra hardware.
Haven't tried cross compiling anything yet, sounds really cool. Nice work on the Mandelbrot demo!
You shouldn't have any problems with CC65 (specially if you're emulating the Apple II!). In my case it took a good amount of work just to get a "hello world" using printf ;)
And re:Mandelbrot... thanks! it took 2 hours and 13 minutes to render that Mandelbrot in ascii :) Because my design with external SRAM I have around 2.2464MHz free after dealing with the video generation (composite video timing is so expensive!), but the extra overhead of the compiler has to be added on top of that (plus fixed float point numbers in a 6502 emulated in an AVR...).
Haven't tried cross compiling anything yet, sounds really cool. Nice work on the Mandelbrot demo!