From: Trifle Menot <triflemenot@beewyz.com>
To: linux-msdos@vger.kernel.org
Subject: Re: serial performance
Date: Sat, 13 Mar 2010 13:53:12 +0000 [thread overview]
Message-ID: <201003131353.o2DDrFOF029406@beewyz.com> (raw)
In-Reply-To: <4B9B4114.2000802@sat.dundee.ac.uk>
On Sat, 13 Mar 2010 07:39:00 +0000, Paul Crawford <psc@sat.dundee.ac.uk>
wrote:
>Trifle Menot wrote:
>> With that setting, PCBoard now sees a 16550 when using /dev/ttyS0, and
>> my remote output looks fast, like 57600 should. So poking the necessary
>> bits into the dosemu virtual UART fixed things up.
>Can you elaborate on which bits you poked to achieve this?
>We have also had some performance issues with the virtual UART and
>anything that makes it more like real-time would be appreciated.
I'm not sure, but probably UART FCR0=1. I got the idea from reading
PCBoard's help text for the "Force 16550A Usage" setting:
> Some multi-tasking environments, such as OS/2 or Windows, use device
> drivers to virtualize the comm port. In the process of doing so, they
> may hide the 16550A UART, making it appear to be a 16450 UART when
> accessed by a DOS application.
> Setting the answer to 'Y' tells PCBoard to operate AS IF it had
> detected a 16550A chip.
From a quick read of the dosemu source, it seems that the virutal UART
defaults to 16450 mode, until you put it into 16550 mode, presumably by
poking FCR0=1 into the (virtual) UART.
If the app cannot do that on its own, maybe a small C program that does
it, prior to launching the app, would achieve the same result.
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prev parent reply other threads:[~2010-03-13 13:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-12 15:57 serial performance Trifle Menot
2010-03-13 5:12 ` Trifle Menot
2010-03-13 7:39 ` Paul Crawford
2010-03-13 13:53 ` Trifle Menot [this message]
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