[Coco] Bitbanger port interfacing

[Arthur Flexser]

There's a couple of pokes that are needed to the ROM printer output
routine, and the situation is simplified by the fact that it's a CoCo 3,
where the routine runs from RAM.  I don't have the pokes handy, but perhaps
someone will step in with them.  They've been mentioned in some previous
threads.  You basically (no pun intended) have to change a conditional
branch to an unconditional one in a couple of places.  Looking at the
disassembly of this routine, which is somewhere in the low $Axxx region, in
Color Basic Unravelled, available by googling the title, may be enough to
tell you what's needed.

Art

On Fri, Nov 9, 2018 at 11:27 AM, Adam Coolich <adamcoolich at hotmail.com>
wrote:

> I'm attempting to read/write data from a PC to my Coco3 through the
> bitbanger port. I've had some success utilizing a terminal program on the
> Coco3. I'm using Microsoft Visual Studio, which has some easy-to-implement
> serial communication protocols. Sending data to the Coco is a breeze.
> However, I'm struggling to overcome the Carrier Detect on the Coco when
> receiving data. I assume that the Coco is looking for a steady voltage on
> the CD line to let it know that the "printer" is on (for commands like
> PRINT #-2 and LLIST). Unfortunately, my programming chops aren't
> sophisticated enough to overcome this in software on the PC end.
>
> I suppose I could mock up a small breadboard to supply a steady +5V to the
> CD line, but I'd rather not resort to that.
> Is there a POKE that will trick the Coco into thinking that the CD line is
> active (i.e. printer is on when it isn't)? I've looked through a lot of the
> available literature on the archive and haven't found anything.
>
> Thanks!
> Adam Coolich
>
>
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