[Coco] The Trials to disable RS232 Status

[David Ladd]

On Sun, Oct 1, 2017 at 12:13 PM, Barry Nelson <
barry.nelson at amobiledevice.com> wrote:

> > Darren A
> > Sun Oct 1 11:44:13 EDT 2017
> >
> > On Sun, Oct 1, 2017 at 2:19 AM, Arthur Flexser wrote:
> > > Another method of bypassing the RS232 status check is these pokes:
> > >
> > > POKE &HFF23,&H30: POKE&HFF22,&HF9: POKE&HFF23, &H34
> > >
> > > This will work on any model CoCo, does not depend on what ROM version
> > > exists in the machine, and does not require copying ROM to RAM.
> > >
> > > I works by using the PIA's data direction register to change the
> relevant
> > > status bit in $FF22 from an input to an output, so that the RS232
> status is
> > > always seen as "ready" by Basic.
> >
> > But wouldn't that be potentially damaging to the CoCo?  You are
> configuring
> > the PIA pin to be an output driving the line low, while the SALT chip (or
> > OpAmp) will be driving it high, essentially creating a short-circuit.
> >
> > - Darren
> According to the schematics I have for the CoCo 3 I would tend to agree
> with Darren that using those setting could be a bad idea. It looks like the
> SC77527 (U8) chip is wired directly to the 6821 (U4) with no resistors or
> other components in between.
>
> I also found this hook which might be useful…
>
>  $0170-$0172 Output to DEVN using PRINT (DOS SuperDosE6 JMP $c29c)
>

​Hmm interesting idea. Not familiar with stuff yet :) So many avenues that
a person can take to do the same job.​



>
> Perhaps by changing the address of this jump hook to your own routine you
> could do something...
>


​This jump hook stuff sounds good too. This is something I haven’t done.
Might be a good topic to bring up in a Assembly primary or basic stuff of
how to over ride stuff :)​



>
>
>
>
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​

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