[Coco] 6809 disassembly help wanted

[Allen Huffman]

> On Nov 21, 2025, at 2:53 PM, Sean Conner via Coco <coco at maltedmedia.com> wrote:
> 
>  The array mb_sec34_1 is fine; Jerry's disassembly is wrong.  I ran the
> array through a disassembler I wrote [1] and got a cleaner result which
> translates to (and using documented Radio Shack values) [2]:

Jerry’s perl script (which I think he put together just for this, using op codes from a 6809 book) had issues with something that threw it off, and the Z-BUG disassembly I worked with had other issues. I did not realize this was that difficult.

John Linville pointed me to f9dasm and I have been figuring it out. It does a much better job, and lets me provide an “info” file to tell which areas are data versus code, and name labels and such. It is producing much better results.

BUT, when I started tackling the multiboot code, f9dasm creates something I don’t recognize:

Z3908   DEY                              ;3908: 31 3F          '1?'

What the heck is DEY? Is that even a thing???

A bit further down, it did this:

        PSHX                             ;396F: 34 10          '4.'

I am not sure if this is a bug in the program, but neither of those is recognized by the assemblers I tried. The default to f9dams is -6809 and you have to use other options to change it.

https://github.com/Arakula/f9dasm

Getting closer though!

I know nothing about DSKCON so this will be a fun learning exercise to see what it does (and blog posts, no doubt).

Thanks! I am going to compare your listing to what f9dasm did and see if there are any differences.

I had no idea what the two scratch pad variables at D1 and D3 were for, so your comments are helpful.

		- A