It might just simply be that DR DOS 3.41 doesn't support CD drives. It was released in 1989, which would suggest it might be possible. After all, MS DOS 3.1 could already run MSCDEX and support CD-ROMs, from what I read on Wikipedia. And that was a couple of years earlier! I would try NWCDEX nevertheless. It is supposed to be pretty good and light on the conventional RAM. Also you might want to check if there were different DR DOS 3.41 releases, maybe another one will work. Otherwise you can also try and jump ahead to DR DOS 5.0 just for testing purposes and see if that changes anything.

Tried it in VirtualBox and got the same problem with DR-DOS 3.41. Also used OAKCDROM.SYS but used MSCDEX.EXE version 2.25.

Don't know what the problem is but my guess is with the unsupported MSCDEX (or alternatives) calls. Needed to set the /L:D parameter for example. If not it would try to use A: as drive and make drive C: not accessible anymore etc.

DR-DOS 5.0 and 6.0 work correctly with these files and versions btw.

Yoghoo wrote on 2022-06-24, 11:33:

Tried it in VirtualBox and got the same problem with DR-DOS 3.41. Also used OAKCDROM.SYS but used MSCDEX.EXE version 2.25.

Don't know what the problem is but my guess is with the unsupported MSCDEX (or alternatives) calls. Needed to set the /L:D parameter for example. If not it would try to use A: as drive and make drive C: not accessible anymore etc.

Thanks for testing with MSCDEX version 2.25 and on VirtualBox.
I don't think the problem is based on MSCDEX. If that were the case, SHSUCDX.COM (from FreeDOS) could have worked, but that doesn't work either.
I think the problem is right at the beginning when one of the CD-ROM drivers loads.
See the error message from UVDV2 above.

DR-DOS 5.0 and 6.0 work correctly with these files and versions btw.

Thanks for the information.

root42 wrote on 2022-06-24, 11:31:

It might just simply be that DR DOS 3.41 doesn't support CD drives. It was released in 1989, which would suggest it might be possible. After all, MS DOS 3.1 could already run MSCDEX and support CD-ROMs, from what I read on Wikipedia.

As far as i know, MSCDEX does make use of the Microsoft networks interface in MS-DOS which was introduced in MS-DOS 3.1. Maybe DR DOS 3.41 doesn't support such an network interface?

And that was a couple of years earlier! I would try NWCDEX nevertheless.

But what should i do with the error message of UDVD2 earlier?

Also you might want to check if there were different DR DOS 3.41 releases, maybe another one will work.

Is it somehow possible to read version informations from the files DRBIOS.SYS and DRBDOS.SYS?

Can you still try NWCDEX though? Just for kicks, and to confirm that 3.41 just can't do it?

Exploit wrote on 2022-06-24, 11:46:

And that was a couple of years earlier! I would try NWCDEX nevertheless.

But what should i do with the error message of UDVD2 earlier?

I don't think you need to use UDVD2... Just use one of the other CD drivers plus NWCDEX from e.g. DR DOS 7.

root42 wrote on 2022-06-24, 11:48:

Can you still try NWCDEX though? Just for kicks, and to confirm that 3.41 just can't do it?

Ok, i searched on my old Shareware CD-ROMs and found version 2.20 of NWCDEX.EXE and some other files in the ZIP file, like newer versions of CHKDSK.EXE and DPMS.EXE.

I tried it now in my DR DOS 3.41 VM and used the same parameters as with MSCDEX.EXE and it has the same error message. See the screenshot.

root42 wrote on 2022-06-24, 11:49:

Exploit wrote on 2022-06-24, 11:46:

And that was a couple of years earlier! I would try NWCDEX nevertheless.

But what should i do with the error message of UDVD2 earlier?

I don't think you need to use UDVD2... Just use one of the other CD drivers plus NWCDEX from e.g. DR DOS 7.

Okay, used the OAK CD-ROM driver again, but it's the same problem:

Also tried some other versions of MSCDEX and CD-ROM drivers from LG etc. But couldn't find a working combination. 🙁

It's probably safe to say that DR-DOS 3.41 just doesn't work. Try DR DOS 5.0 and see if that helps. That is more in the era of CD-ROM anyway.

Found this interesting German text about NWCDEX.EXE
http://www.antonis.de/dos/dos-tuts/mpdostip/h … ml/nwdostip.htm

It says about NWCDEX.EXE:

1NWCDEX.EXE    Speicheroptimierter (weil DPMS-nutzender) Ersatz für
2                 Microsofts MSCDEX.EXE, siehe auch Kapitel II.3. und V.4.
3                 Arbeitet auch mit DR DOS 5.0 und 6.0 (nicht aber mit 3.41).

Sloppy translation in English:

1NWCDEX.EXE A memory optimized (DPMS using) replacement of Microsoft MSCDEX.EXE. See chapter II. 3. and V.4.
2                           It does work with DR DOS 5.0 and 6.0 (but not with 3.41)

Maybe DR DOS 3.41 doesn't have that network interface, that MSCDEX.EXE or NWCDEX.EXE requires? That's at least the only explanation i have at the moment.

That's very much probable. Hence my recommendation to go to DR DOS 5.0. I would assume you didn't use 3.41 with a CD ROM back in the day either. So not much nostalgia lost here. 😉

root42 wrote on 2022-06-24, 12:48:

That's very much probable. Hence my recommendation to go to DR DOS 5.0.

Never mind, by using a VM i can also copy larger amounts of files on the guest hd image by just mounting it on the host system. Another option is to just boot a live-cd of FreeDOS and copy the files from a second virtual CD-ROM on the DR DOS hd image when FreeDOS is running.

I would assume you didn't use 3.41 with a CD ROM back in the day either. So not much nostalgia lost here. 😉

That's true. At that time my family already had bought MS DOS 6.2 and i could play Rebel Assault, my first game shipped on CD-ROM. 😀