Great project! I released my own Arduino based microcomputer today and it is interesting that we implemented similar things in a different way (eg, I implemented composite video and not VGA; how different would have been my project if I had gone the other way!).
I discarded early on emulating a complete machine, so I just emulated the 6502 CPU and focused on getting CC65 cross-compiler working with my machine. I'm impressed you managed to emulate the Apple II. Kudos!
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...).
"Emulating the 6502 is in itself is a significant undertaking so this phase took on the order of a week or two."
Don't know if the author was bragging or what, but it reminds me of the fact that Woz designed and created all of the hardware and software for the original Apple and Apple II. Nicely done for it's time. I wonder if anyone can create something would be equivalent to today's systems.
Author here. I meant that in earnest, getting the emulator 6502 compatible was a large part of the project. But it did come together in about ten days, on the order of 70 hours.
There's something about these old systems, you can fit the whole system into your mental working memory. Just can't do that with todays abstractions.
The 6502 is a beautiful CPU, but is really simple too. I took me 5 days (let's say 10 hours) to get my 6502 VM working and passing Klaus Dormann's functional tests.
This is seriously nice. We keep hearing about how much more powerful today's processors are compared to yesterday's stuff. Here is a project that demonstrates that power.
I discarded early on emulating a complete machine, so I just emulated the 6502 CPU and focused on getting CC65 cross-compiler working with my machine. I'm impressed you managed to emulate the Apple II. Kudos!