On 2009-04-06, at 15:34, Jim Brain wrote:

>> I am not really sure if I understand correctly - are you trying to  
>> understand the electrical properties of the interface out of the  
>> C2N232 code? Again I am not sure if I got it right but isn't the 64  
>> schematics a better source of this information? AFAIR (I don't have  
>> the schematics at hand now) there is nothing really special about  
>> it except that one line is IRQ capable and the motor power is a  
>> clumsy TIP29/Zener combination, which doesn't really fit into  
>> digital (TTL) IO and may require extra handling.

> No, the electrical properties are not so much a mystery as the  
> protocol.

Ah, OK. The protocol is in fact a different beast and not really a  
typical one. Here I believe Marko is the best to tell more about. I  
once wrote "The Finaltape". A highly extended turbo based on other  
implementations but I never really touched the original CBM  
implementation. It was so inefficient that I never felt like even  
having a closer look ;-)

> There is this:
>
> http://www.zimmers.net/anonftp/pub/cbm/crossplatform/transfer/C2N232/firmware/c2n-format.txt
>
> But, I'm looking for an article or other reference that goes into  
> more detail (read: the quick document above did not make sense to me)
>

I think there was more in Marko's docs for the C2N232 but in the worst  
case you probably don't _have to_ completely understand the protocol  
on the C2N side as Marko's implementation works great. Of course I  
don't say that gluing it with the USB side would be trivial but should  
still be possible?

> There were a document on the C64 Tape preservation project site, but  
> they waved their hand over the CBM stock routines, stating they were  
> more complex than many tape loaders and then they went on to  
> describe how tape loaders for games work.

Yes. That was where everyone's interest was. The standard routines  
where used only to bootstrap a "proper" (faster/more reliable) loader.

-- 
SD!


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