[Coco] Making BASIC not wait for printer.

[Arthur Flexser]

To elaborate, now that the memory of this somewhat comes back to me:

The first poke, to $FF23, causes $FF22 to become the data direction
register, temporarily replacing $FF22's normal operation.  The second poke,
to what has become the data direction register, sets the bits of $FF22 to
the pattern of inputs and outputs that is desired.  Then the third poke, to
$FF23, turns off the data direction register, restoring the bits of $FF22
to normal operation.

There should be a fourth poke, setting $FF22 to zero so that the new output
bit contains the correct value to tell Basic's printer routine that the
serial port isn't busy; at least there was in the version I used years
ago.  Probably this final poke can be safely omitted, at least under DECB,
since it would be unlikely that the serial port would register as busy at
the time the data direction register was activated.

Art

On Sun, Mar 26, 2017 at 3:27 PM, Allen Huffman <alsplace at pobox.com> wrote:

> Years ago, I found POKEs that would make BASIC not wait for the printer,
> allowing you to PRINT#-2 to the bitbanger port to output to a modem.
>
> POKE 65315,48
>
> POKE 65314,249
>
> POKE 65315,52
>
> Hardware was a mystery to me back then, and now that I know a tiny bit
> about it, I wonder what is going on with these POKEs.
>
> Anyone care to enlighten me?
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