[Coco] Hello Aaron help dragon

[Aaron Wolfe]

On Tue, May 17, 2011 at 11:55 AM, Darren A <mechacoco at gmail.com> wrote:
> On 5/17/11, Phill Harvey-Smith  wrote:
>>
>> I believe that I checked this and the only thing you should need is to
>> make a level shifter, I think the PIA pins that the CoCo uses as bitbang
>> inputs are ACK and BUSY on the Dragon. So yeah I think that a simple
>> MAX203/232 adapter would be suffient, there's even a +5V output on the
>> Dragon paralell port to run it from.
>>
>
>
> The Dragon's BUSY and ACK inputs are connected to the same PIA pins as
> the CoCo's RxD and CD inputs respectively.  The STROBE output on the
> Dragon is connected to the same PIA pin as the CoCo's RxD output, but
> is also inverted. The only change needed in the code would be to
> handle the inverted data output. This could optionally be dealt with
> by the server.
>

This sounds promising.  Was there ever an HDBDOS for Dragon?  I'm
guessing not.. what would be involved in getting the bitbanger
routines into a Dragon compatible DECBish ROM?  As I recall there are
some differences with rom routine locations and the keyboard stuff,
maybe more.