6502.org

It would be curious to be able to capture the actual results and compare the diagrams amongst the different systems, see what if any changes there are (most likely from the FP implementations).

Right!

What's the trick to porting BBC Basic?

That's easy - just write an Acorn compatible operating system....

Mines at 6K and growing. (Acorns was about 14K) However to make Basic work, you need the bare minimum - a BRK handler and 3 "OSBYTE" calls. Oh, then you need an OSWORD 0 handler (read line of text). Then .... Start here: http://mdfs.net/Software/BBCBasic/6502/ and ...

And ... er ... good luck getting out of that rabbit hole...

I have plans to open source my works at some point, but I need to do some tidying up and re-arranging of the code somewhat. I've also ran out of room, however that's only because I was looking at TaliForth's 24K executable, if I ignore that (which I probably will), then I have just under 16KB of operating system space. (Memory is $8000-BFFF: Language ROM, $C000 -> $FFFF: OS ROM - Ruby has hardware IO in $FE00-$FEFF and the top 128 bytes of $FF80 are the Ruby/Acorn OS Vector entry points.

Cheers,

-Gordon

That's very good point... And I've just checked - and They're identical. they may differ in deeper magnifications or with a greater number of "colours" in the pallet, but for the text version all come out the same.

-Gordon

This is MOS clone I wrote for my PIC24 6502 emulator. It contains a little more than the bare minimumm but not much more.

https://github.com/andrew-jacobs/em-ret ... os/mos.asm

Thanks for the Mandelbrot code. I modified it to generate a 100x75 16-color version on my FPGA-based 6502 system

Very nice!

One thing to watch out for in BBC Basic is that screen coordinates are not necessarily pixels. So, depending on the actual screen resolution, the X and Y increments might be by 2 or 4 units rather than 1. Get this wrong, and it all looks fine but runs much slower than necessary.