DOS Games Discussion

When I create a directory called "C:\DRIVERS\CDROM", I am unable to access it. Shoots me an error "invalid directory" Any folder called "CDROM" shoots back that error. I'm stumped.

Choose another dir name.....

falls under "yep shit happens"

It's very weird. I'm blaming it on the CPU. I have other DOS machines and I have never seen this.

Sure there isn't a /drivers/cdrom/ installed by some external prog?
Flagged read only-sys-hidden?

Whatever, if you ever find out why let us know.

I don't see how. My process of building a DOS 6.22 PC is "format c: /s" Then I make 4 directories. MOUSE, CDROM, SBBASIC, and CTCM. Copy over drivers from a self-made Driver CD. Nothing is different this time. Not too mention that on the Driver CD is a folder called CDROM too and it gives me the same error. I've used a IDE HDD with a 500MB partition and a CF Card 256MB. Both have the same problem and both were in different machines at one time. Frustratingly odd.

Weird? Yes.
Strange? Yes.

And yet I won't let my sleep for it.

As said before: shit happens.

Catched an old dos virus?

Caught an old virus? lol Wouldn't that be something.

I wasn't able to resolve this but I think I have narrowed it down. It seems when the CDROM driver is loaded in config.sys, it makes all folders named CDROM unreadable. Very weird.

Makes sense, actually. DOS checks device names before directory names, and both devices and directories use the same "file" access APIs. Reading/writing data from a device is the same as from a file, since the disk is really just another device...

Ergo, if your cdrom device driver is loaded, it will mask any directory of that same name. There are a few other similar names that are blocked for that reason, not 100% sure what they are, but things like CON and PRN.

I'm not certain, but it's possible you can rename the actual CD device driver in-memory name as a commandline arg to the config sys or autoexec driver. If you really want a "cdrom" directory, it might be worth a try or some research. Then name it cdrom1 or banana or asdfqwer, and *that* name will be blocked instead. As I recall, you specify that in the driver and in the mscdex commandlines, but it's been a loooong time, so ymmv.

I think I recall a generic cdrom driver boot disk that tried to load a bunch of common drivers and named them all banana; that covered access for like 80% of the drives out there but it took me too long to figure the banana thing out - just a silly unlikely name.

Actually, I think the problem still exists in Windows. I was getting a weird bug testing some software, and we tracked it down to this bizarre and obscure (but documented) behavior; that's how I know about it. That's what I get for trying to name the print-to-file output directory PRN. During our research, we found out it went back to Dos 1.0, and may be true in CP/M and Unix as well.

Hope that helps, sorry for the tl;dr history lesson.

Makes sense Quadko.

For those interested:
CDRom drivers need config.sys and autoexec.bat comm lines.

Basic CD driver +'device name' config.sys:
example:
DEVICEHIGH=C:\DOS\cdrom.sys /D:name001
/d: defines driver name

Must match with autoexec.bat mscdex
LH C:\DOS\MSCDEX.EXE /D:name001 /l:D
/d: must match config.sys name.
If more than one CD drive should be : name001 - name002 - etcetera....
/l: drive letter

Pour moi, never had a CD driver who was named as 'CDROM', still a weird idea, 'bananas' on the other hand, plenty of them........
Also lots of 'MSCD001' -002-003 ........, when used in multi CD-DVD drive systems, keeps things a bit sorted out.

Rodimus80, if you wanna keep that 'cdrom' device name simply add a number, something as 'cdrom01' ... whatever suits you.

Thanks, dosraider! I'm glad you've got the details, that should help a lot.

And it brings back memories. "mscd001" - I sure remember that in particular. And Oak cdrom drivers.