[Coco] DriveWire survey

[CoCoList for Color Computer Enthusiasts]

On May 11, 2014 3:32 AM, "CoCoList for Color Computer Enthusiasts" <
coco at maltedmedia.com> wrote:
>
> On 5/11/2014 2:14 AM, CoCoList for Color Computer Enthusiasts wrote:
>>
>> Looks like the CD line can trigger an IRQ.  Is that what you were
>> thinking  Buffer some bytes in a uC, trigger the Coco, and it asks for
the
>> data?
>>>
>>> Or, are you suggesting a cartridge that will IRQ when there is data to
>>
>> receive?
>>
>> More the latter.  I think there is an issue with the interrupt that CD on
>> the bitbanger can trigger that makes it not suitable, but I don't know
the
>> exact details.  Unfortunately I am not very well versed in the hardware.
>
> Good, because I think that approach has limited runway.
>>
>>
>>> Was there an official UART cart and is the schematic available anywhere?
>>
>>
>> It doesn't have schematic but does have some info about the pins on the
>> cartridge,dunno if that helps.  Somebody on the list might know where
more
>> info lives if its around anywhere.
>
> No worries.  I got what I needed.
>
> 6551 register set (same as the CBM folks), FF68-ff6b address space...
>
> Let me see if I can put together a replacement, as it would be fastest to
develop...  The stock 6551 can do 115200 and will signal IRQs on each byte
received.
>
> I assume DW4 does not suport the RS232 cart right now?
>
>
> Jim

There is or was limited support for 6551s at one point, but the version
used in the Tandy rs232 pak was limited to 57,600 bps for some reason and
the driver/protocol doesn't take advantage of the interrupt so would still
poll if it even works.

In any case, drivers do exist and can probably be fixed up to work without
much effort.