I have been trying to add a dvd drive to my computer but can't seem to get things working properly. I'm running PIII 900 mhz 256m ram. Slackware current. Before putting the dvd in my system, the cd worked fine. Now I can't read either drive. I have tryed re-installing several times with different kernels with no luck. The funny thing is, during installation the system will detect and install from either drive with no problems. During boot up is see both drives listed i.e. hdb cdrom, hdc dvdrom.

Here is my /etc/fstab listing

/dev/hda1 swap swap defaults 0 0
/dev/hda2 / reiserfs defaults 1 1
/dev/cdrom /mnt/cdrom iso9660 noauto,owner,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
proc /proc proc defaults 0 0

any help would be appreciated

Try mounting them directly (as root):
mount /dev/hdb /mnt/cdrom -t iso9660
mount /dev/hdc /mnt/cdrom -t iso9660

Nope, didn't work. hdb says no such directory. hdc says too many file. I should have mentioned the cdrom is installed as primary slave the dvdrom is secondary master. I have checked and rechecked jumper settings to make sure they are correct. Also the light on the dvd blinks constantly, even with no disk installed. Another funny thing, I can put a music cd in either one and use the play button on the device and it plays through the sound card fine. But only one at a time, i.e. I can put a disk in both play from one but then I can't stop it and play the other.

If you weren't answered yet on this,this may help.
I had the same thing happen (kinda).
I installed slack with the scsi.s kernel,because in the forum there were references as to a dvd needing a scsi driver type interface instead of the normal ide kernel for dvd and cdrw drives.
Seems that the drives are seen as
master 1 hda
secondary 1 hdb
master 2 hdc
secondary 2 hdd
What I did was in /etc/fstab call out the devices as
dvd /dev/hdc /mnt/dvd auto noauto,users.ro 0 0
cdrw /dev/hdd /mnt/cdwriter auto noauto,users.rw 0 0
Then add them to the /mnt directory as dvd and cdwriter
This didn't work as I liked so I used

dvd /dev/scd0 /mnt/dvd auto noauto,users.ro 0 0
cdrw /dev/scd1 /mnt/cdwriter auto noauto,users.rw 0 0
This worked nice so I printed it out for reference.
Took me about 3 days to figure it out,lol ,but I'm learning.....

OK, what I did, I removed the cdrw temporarily from my system. Now I have Hda=harddrive, hdb=dvd. I edited my /etc/fstab for the dvd as you listed. in the first part of your answer. (I tried making it /dev/scd0 but the system didn't like that. I couldn't mount the drive.) now I can play a cd in the drive but if I put in a DVD Xine says it can't read the drive or I don't have permissions.

Thanks for your help I seem to be closer than I was.

Looks like your hard drive is master on channel 1 and the dvd is slave on channel 1.
If you put your writer on channel 2 as master, you should have /dev/hdc.
If you use slave on channel 2 would be /dev/hdd.
Makes sense after you see it a couple of times.
I finally made sense of it after reading the forum messages and looking for patterns in hardware others had.
What finally helped the most was looking at the info that each boot produces, in /var/log/messages.
This file is written to each boot,and if your machine is quick like mine,you can't read the boot process very well. The file has a few of the last boots and the current boot at the bottom ,so you can referr to it in a calm and calculating fashion.
It is packed with information about what went on while you were trying to speed-read the boot process.
Hope this helps.
I am enjoying this forum a bunch,and it has answered most of the questions I have encountered very well and fast!
.........Mick

It is helping more than any thing else I have tried. I'm a little confused on what I need to make this thing play movies. Some places I read that scsi emulation is needed and others say not any more. I also saw a post that said I may need another file that Slack doesn't install, but I forgot where it is located and the file name. ( I research this at work when I have the time also and didn't print out the message )

Another thing I haven't quite figured out is how to make sure it is properly set up in the /mnt directory and links are correct.

Scsi emulation is required in kernel 2.4, and redundant in kernel 2.6 for CD-RW/DVD±RW.
What I used to do when I had a DVD-ROM and a CD-RW was set both up to use scsi emulation with the apend line in my lilo.conf.
The first drive to be detected will be sr0, the second will be sr1, you can check this with the command "dmesg | grep scsi",
(I only have a DVD±RW now which is why there is no sr1).
In your fstab you'll need entries based on sr0/1 instead of hdb/c, create seperate mount points for each drive, eg: /mnt/cdrom and /mnt/dvd and you'll need to recreate the sym links in /dev to point to the scsi devices instead of the ide devices.
Remove the existing link(s) and recreat them as follows, (as root)
If you don't have a dvd link then you can ignore the "rm dvd" part, and replace sr# with the correct device for each drive.