Why do you want to set FILES=40?
Who told you to do so? And why should it be necessary?

I want to set files=40 since I'd like to run a software that requires to set this inside the config.sys file. I guess a number more than 40 also should do.

dosbox internally sets files to something like 128 I think

Try the dosbox 0.65 release if you didn't already, otherwise the
name of the program might be helpful.

Internally DOSBox already allows for a very high number of open files (more than 50 I think).

So unless your software tries to examine config.sys for a line that says files=50, there is no need to worry.

Thank you so much for your answers. This means I've got to look for the problem-solution somewhere else. When I found it - I will tell you.

The programs name is "Bildfahrplan" (a graphical timetable editor).

What is the error message? You could try making a dummy config.sys file with FILES=40 in it and see if that makes the program happy.

Yes, this was the first I did. The program did check the config.sys. With this dummy config.sys the program continued but then stopped. Nothing further was possible. The first idea was that the program tried to open too many files. I assumed that this might not be possible since the config.sys just was a dummy-file.
Another reason might be that the screen settings do not fit. But the author of this program and I checked: Both is in VGA-mode (DOSBox and the program).
The author offers the following settings:
no Super-VGA-board (this shall be VGA only)
Genoa Super-VGA
OAK Super-VGA OTI 067 or similar
Paradise Super-VGA
Sigma Super-VGA
VESA Super-VGA-board
VGA with ET3000/ET4000-chips
VGA with T89000-chips
Video Seven Super-VGA

May be another setting might make sense? I tried some but it didn't.

Hauke

It could be a problem where the program is trying to detect if DOSBox has a serial or parallel port (for printing the timetables). Games usually don't bother with printer ports, but this program might be different.

I will check this. But I do not really trust in this possibility since printing would occur in a far later stage when the user chooses to print. The author implemented postscript printing directly in a file since most users do not have the printers any more for his old "printer drivers". So the program should never check the ports when the user is not requesting to print.

Another idea: May be the program fails to open, copy or add information to some files??
This idea stems from the experience that the "dir"-function does not show files when I added them into the mounted disk not from DOSBox but from the UNIX level. I can start these programs, because I know the name exists; but <dir> doesn't show them unless I restart DOSBox.

Hauke

Yes, DOSBox don't want to spend time constantly monitoring what the underlying system does to "it's" filesystems, so it won't notice the new files unless you tell it to do so.

From the DOSBox Read-Me file:

1================
25. Special Keys:
3================
4
5ALT-ENTER     Switch to full screen and back.
6ALT-PAUSE     Pause emulation.
7CTRL-F1       Start the keymapper.
8CTRL-F4       Change between mounted disk-images. Update directory cache for all drives!
9CTRL-ALT-F5   Start/Stop creating a movie of the screen.
10CTRL-F5       Save a screenshot.(png)
11CTRL-F6       Start/Stop recording sound output to a wave file.
12CTRL-ALT-F7   Start/Stop recording of OPL commands.
13CTRL-ALT-F8   Start/Stop the recording of raw MIDI commands.
14CTRL-F7       Decrease frameskip.
15CTRL-F8       Increase frameskip.
16CTRL-F9       Kill dosbox.
17CTRL-F10      Capture/Release the mouse.

CTRL-F4 might help here.

CTRL-F4 (in my case I also tried CTRL-APPLEKEY-F4) doesn't help.

DOSBox dis not crash: All other CTRL-Fx keys do work.
I guess: Even the program did not really crash since in the readme is mentioned that if a program crashes DOSBox will kill itself. Is this right?

But I do not really trust in this possibility since printing would occur in a far later stage when the user chooses to print. The author implemented postscript printing directly in a file since most users do not have the printers any more for his old "printer drivers". So the program should never check the ports when the user is not requesting to print.

Please check this with the author, I just had a look and the program description says that it needs a "real" printer connected to the parallel port and that for graphical prints there is the possibility for using postscript. But it still could be that the program checks for a real printer and normally is content with the answer it gets when there is no printer but doesn't like what Dosbox says.