I noticed several threads at this site discussion problems with configuring sound in Slackware. I read them all, and used them to fix my machine. I thought giving you this information may help the next poor soul who loads Slackware without any sound. My system is a Dell Dimension 8250, probably a P4. Here are my notes:

Sound
alsactl [options] [command]

location: /usr/sbin

Commands

alsactl store; saves current driver state to the config file called asound.state
alsactl names; generate list of available device names and save it to the config file called asound.names
alsactl restore; loads driver from config file; this is usually executed at boot up

Options

-h help
-f file, select config file to use (if not specified, the default is used)
-F Force, use with restore to restore matching control elements
-d debug, verbose
-v version, print version number

Configuration files

etc/asound.state; config file (default)
etc/asound.names; store list of devices available in the system

See also

alsamixer; to set the volumes on the sound card
amixer; command line version of alsamixer
gamix; an alternative to alsamixer
aplay; used to play a cd disc
kamix; volume on kde
alsaconf

Example:

First, go to /usr/sbin
alsaconf*; to configure the sound card; follow the prompts

Then, go into /etc

alsactl store; generate the file asound.state
cat asound.state | more; read the file
alsactl names; generate the file asound.names
cat asound.names | more; read the file

alsamixer; set volumes on sound card
reboot computer
alsamixer; establish that the volumes are up.

You may have to go to /dev and issue this command:
chmod 777 audio0
chmod 777 mixer0; for the sound card to work for other users

Device on the Dell Dimension 8250:

To get the name of the driver, you can issue the following command:
Lspci | grep audio

Card: Intel 82801BA-ICH2; ACí97 Audio
Chip: analog device AD1981A

Ref: http://www.die.net/doc/linux/man/man1/alsactl.1.html