Re: Plus/4 RS232 woes

From: Mia Magnusson <mia_at_plea.se>
Date: Mon, 3 Sep 2018 22:08:05 +0200
Message-ID: <20180903220805.0000792d@plea.se>
Den Mon, 03 Sep 2018 10:14:53 +0200 skrev André Fachat <afachat@gmx.de>:
> Hi Bo,
> 
> Am 3. September 2018 09:52:20 schrieb Bo Zimmerman <bo@zimmers.net>:
> 
> > Hello all,
> >
> > After check both(!) books on Plus/4 programming, and the 6551
> > schematic, and doing experimenting... I have a question.  Does
> > anyone know the kosher way to change the user port RTS signal so
> > that the modem knows to stop transmitting data while a program
> > catches up?  I'm initializing the Command Register to 5 (RTS
> > low/enabled, DTR enabled, IRQ, no party, no echo).  But bad things
> > seem to happen when I attempt to touch it again to change RTS to
> > high/disabled.  Does anyone have any knowledge or experience with
> > this?
> 
> In my experience the rts/cts/dtr lines are completely broken in the
> ACIA.
> 
> They switch off rx and/or tx at inconvenient times and in the middle
> of transactions.
> 
> So no, I don't know a good wayof using them, sorry

The A2232 7-port serial card for Amiga uses the 6551 and it seems to
think that CTS and DCD is really broken and uses a separate 8520 CIA
instead of the 6551's for those signals.

Btw this is probably well known but there is an alternative driver
available on Aminet which afaik is a complete rewrite, making that card
able to run at 115200 on it's fist two ports with no data loss and
almost no cpu load on the Amiga.

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Received on 2018-09-03 23:00:05

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