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List:       freedos-user
Subject:    Re: [Freedos-user] Question about error message / redirecting AUX and PRN?
From:       Eric Stein <thebr () indnile ! com>
Date:       2022-07-11 17:25:26
Message-ID: e401589e-bd4a-e208-368e-51e8eecd0fa6 () indnile ! com
[Download RAW message or body]

Thanks for the reply. It turns out the software is trying to write to 
the com port on exit, which I'm assuming expects to find a modem there. 
There was a modem connected, but wasn't turned on. With the modem on, I 
don't get the error. Also if there is nothing connected to the port, the 
data is just sent out to nowhere, and there is no error. I'm not sure 
why it is accessing a modem only in certain conditions, but obviously 
this is not a FreeDOS problem.

BTW I did not specifically mention that I'm running this on old hardware 
(Pentium III based) and not a VM. I will ignore the drive messages and 
see what happens. Also it is a Gateway system, so it may have finicky 
stuff going on that a generic system doesn't.

Regards,
Eric

On 7/8/2022 16:29, Eric Auer wrote:
>
> Hi ERIC,
>
> the AUX device usually was the same as COM1, in the same
> way that the PRN device usually was the same as LPT1.
>
> If your program tried to read/write AUX, it either
> really wanted to do something with the serial port,
> or an unrelated bug made it access the wrong file.
>
> According to the FreeDOS kernel sources, AUX is the
> first item in the system file table, similar to
> file handles 0 to 4 defaulting to CON as stdin,
> CON as stdout, CON as stderr, "stdaux" (stdin)
> and PRN, respectively.
>
> Note that your luck may vary when it comes to access
> to real or emulated serial or parallel ports in the
> PC or DOS emulators you may be using today. At least,
> you will have to dig into the configuration docs to
> find out how to link them to the right device of your
> host operating system to make them useful :-)
>
> The message about drives and cylinders probably
> refers to a mismatch between your CHS geometry
> and what would be plausible based on where your
> partitions start and end. The MBR partition table
> should better agree with the geometry reported
> by the BIOS, but if you have LBA, then DOS will
> probably be using LBA instead of CHS anyway, so
> warnings about geometry become less relevant.
> Regards, ERIC ;-)
>
> PS: You are right that our MODE has LPTn=COMn
> redirection but not PRN/AUX redirection. The
> kernel source code says MODE should be able to
> redirect AUX and PRN, like CTTY redirecting CON?
> In MS DOS, the first 3 system file table items
> would be AUX, CON and PRN. I guess redirecting
> those would involve "just" manipulating the SFT?
>
>
>



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