Sure you have mount correct ?

Sure.
I can send you 7zip-packed archive for testing purposes. It is working db. The archive size with empty db is 773,125 bytes.
It's better to see once than hear a lot.

Now, we have that config:
Netware 4.11 file-server --> PC-DOS clients on 1.44-floppies with Netware Client --> database app on Netware's Volume shared as drive O:

I wanna get rid of lockin on Netware and replace it with Linux file-server. DOSBox can mount dirs from linux fs so I simply can mount network share either by Samba or NFS and use that in DOSBox to run clipper app.

Does the "-> 4" refer to DOS error 4, too many open files?

If you've built DOSBox with 250 maximum file handles, why are you limiting Clipper to 100 file handles with the environment variable?

I guess that.

CLIPPER=F100 is because that works in Netware clients and in WinXP. Sure, I have had played with "set FILES" and "set CLIPPER", changed DOS_FILES in the sources. Posting in the forum is the last thing I did after all tries. Maybe, I missed something?

I think the problem is in a something else but I have no experience in debugging DOS progs generally and Clipper apps particularly.

The problem might indeed be elsewhere; however we don't support applications very much. You can't print for example. So it might be useless to begin with.

Nonetheless, it could be beneficial to figure out what goes wrong.

A printing isn't an issue in this case.
Empirical way shows that it's enough to set FILES=13 (!) in CONFIG.NT to run this app in WinXP. To say more, I didn't set CLIPPER variable at all, despite of this that program run and functions (edit: sure, it runs, but some functions fail - so, FILES=13 isn't enough to function properly).

Maybe, the cause is in a method how ntvdm's and msdos's interpreter provides file handlers for programs?

C:\AD2\ad2tab3.NTX
this file is accessable inside dosbox at that exact location ? (with read/write permissions)

Maybe, would it be better if I will give the archive with this app to you for a review? It's less than 1Mb in size.
Just now I've played with FILES's value on my WinXP-workstation. Seems that setting FILES=50 in system32\config.NT is enough to run and use this app. Simply I try to find what is affecting it to prevent run in DOSBox.

Yeah, all files are Ok there. "type" command shows content of any file in dir. "del" command deletes files there.

P.S. Further research shows that FILES=50 is enough to run but CLIPPER variable is required for proper functioning.

So, no solution?

well without having a look at the application itself. There is not more we can do.
You can try running it from a diskimage with a msdos installed on it. but then you loose most of the benefits that dosbox has with regards to using local folders as drives.

Surely. That's what I told about to be allowed.

The key file for it to run properly is INSTALL.MEM

The folder "C:\AD2\" in settings should be set to actual folder for program to function properly. Otherwise, it will not find it's working set files.
Also, CLIPPER=F100 is mandatory.

It runs out of handles in real DOS as well.

As to why the app works in the NTVDM without running out of handles... I can only guess that calls to INT 21/67 are ignored there or otherwise handled differently than real DOS.

When you link a Clipper executable with Blinker, you have the option to "burn in" values from the CLIPPER environment variable, and when you do this the values can't be overridden by the environment variable. It's a feature of Blinker.

For some reason, AD2.EXE has 11 file handles burned into it. If possible, link the application again and either don't specify the number of handles so the CLIPPER environment variable will be used, or specify a higher number. In the Blinker link script there should be a line like:

1BLINKER EXECUTABLE CLIPPER F100;E000

If you are unable to link the application, you can directly modify AD2.EXE to pay attention to the "F" (file handles) portion of the CLIPPER environment variable by changing the byte at offset 99F7h from 00h to 46h.

I ran "keyb ru" to get an appropriate char set, but the app seems to have some complaint about what I guess is a login ID that comes from your AD2.BAT file. However, this is the same thing happening in the above screenshot, so I guess it's not unexpected behavior.

ripsaw8080, you made my day!!! 😅

Thanks a lot to you, changing 0x00h --> 0x46h made it work.
I dunno why it works in WinXP and in PC-DOS without this patching...
In my CONFIG.NT:
SET CLIPPER=F100
SET FILES=100

Our girls use boot-floppies with PC-DOS version 7 Revision 0. I don't realize what is the difference between that and genuine MS-DOS...
I took a look to their config. It uses qemm386.sys, himem.sys along with other stuff.
In config.sys:
SET CLIPPER=F100
SET FILES=100
SET FCBS=4,0
SET STACKS=0

Nevertheless, in this PC-DOS ad2 works without your patching... Moreover, CLIPPER environment variable affects ad2 on my WinXP station too. Dunno these low-level internals, most probably there is some difference there.

The fact is that ad2 works in dosbox now! 😀
Sometimes somewhere it slows down but this is an emulation and I understand.

And you probably guess there are no sources there.

If you don't have the source code, it can be recovered with Clipper decompilers such as Valkyrie. Whether or not you have rights or permission to do so is something you should consider, though.

Some of the other executables have the maximum number of handles burned into them, and therefore ignore the "F" value in the CLIPPER environment variable.

AD2P.EXE = 31
AD2S.EXE = 31
AD2T.EXE = 31
AD2U.EXE = 59
AD2V.EXE = 45

They seem like a more reasonable amount than just 11, though.

About the speed: these programs run in real mode, and so won't automatically be fast with default settings in DOSBox. Set core=dynamic, cycles=max to run them as fast as possible.

Thank you very much again.
With that settings you advised to me it runs much more flawlessly.

Now, I can talk with my boss about buying expensive hardware for M$ Windows(tm) Terminal Server(tm) with Server itself and Windows(tm) Licenses for workplaces of our db operators.
It would be foolish to spend a lot of money for that what isn't worth for it.

you know, there is no file sharing between the instances of dosbox.

Ok, but I run 2 instances of dosbox and run the same AD2 inside each of them. So, I have 2 running instances of the same AD2 in 2 different instances of dosbox. Changes made in one instance are immediately visible in another. So, I think allright and that is what I needed.
What kind of sharing do you mean?

Another question about Valkyrie... Are you running it inside dosbox? I've got error with decompilation trying run it in WinXP cmd-shell.

P.S. It was my mistake. Just don't give file's extention to V.EXE and viola. 😀