[Coco] Javascript 6809 emulator

[Harry Hurst]

>> This may be something already known here, but I just saw a link posted
>> on Hacker News.
>>
>> https://github.com/maly/6809js
>>
>> James
>
> I've been looking over something very similar here:
>
> https://github.com/naughton/mc6809/blob/master/mc6809.ts
>
> It's written in "TypeScript", and is part of a Defender emulator project.
> I'm not certain what the advantage of this TypeScript is because, as I
> understand it, it gets converted to JavaScript before you actually run it.
> It might be like the difference between C and C++? Anyway, if you see any
> blatant errors, or not so blatant, let me know. I have write permissions
> to this project, so if I understand any problems you see in it, I will
> make the necessary changes. I am still trying to figure it out myself. So
> far, I have found only one error in the ROL instruction, caused by a typo,
> and I'm almost certain I have corrected that.
>
> HH
>

I just remembered something I wanted to ask about. In this TypeScript 6809
emulator the author sets the S register to $BFFF on a reset, as well as on
a cold start. I haven't tried to look it up yet, so I don't know, but I
thought it would go to all zeros. It doesn't seem to be a big deal since
the stack isn't used until it has been specifically be set to $9F00, but I
thought I ask a quick question in here. What are the initial values placed
in the registers of the 6809 at start up? I'm thinking all zeros. Does
anybody think, or know, otherwise?

HH