On 2009-04-04, at 01:23, Jim Brain wrote:

> FOr uIEC and C=Key units, I pull power from the cassette port.  As  
> such, I need to provide a small circuit board for the connector so  
> it can be grasped (and to alleviate concerns from some folks that  
> I'm blocking the port for regular use.
> The cheapest idea is to lay out a small PCB that can be soldered to  
> the 6/12 .156" connector and provide the same edge connector on the  
> back.
>
> But, since it will cost the same regardless of the layout, I'm  
> wondering if there is any value in providing some uC functionality  
> on the board, which can be stuffed by oithers, or I can provide at a  
> nomimal cost:
>
>   * C2N232 (or a USB variant) functionality on the PCB

I very much like this particular idea! For me C2N232 is the only  
reliable interface between the 64 and my primary computing platform  
(OS X). I use it heavily every time I do the testing/debugging on the  
real hardware. It would be simply great to have the _true USB_ version  
available!

>   * Small "autostart" that will load and then do a 'load "*",8,1":run
>     or do as the 128 does and load the first 256 bytes of the primary
>     disk.
>   * Something else.
>
> Along those lines, is there a document that describes the tape  
> interface from an electrical perspective.  My AVR ASM is quite  
> rusty, so the C2N232 code is not making much sense to me.

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.

-- 
SD!

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