If your drive is not one of the models listed here, particularly if it was bought recently and is quad speed or faster, it probably uses the IDE/ATAPI interface.
Panasonic CR-521 sbpcd Note 1 Panasonic CR-522 sbpcd Note 1 Panasonic CR-523 sbpcd Note 1 Panasonic CR-562 sbpcd Note 1 Panasonic CR-563 sbpcd Note 1 Creative Labs CD-200 sbpcd IBM External ISA sbpcd Note 2 Longshine LCS-726 sbpcd Teac CD-55A sbpcd Sony CDU-31A cdu31a Sony CDU-33A cdu31a Sony CDU-535 sonycd535 Note 3 Sony CDU-531 s onycd535 Aztech CDA268-01A aztcd Orchid CDS-3110 aztcd Okano/Wearnes CDD110 aztcd Conrad TXC aztcd CyCDROM CR520ie aztcd CyCDROM CR940ie aztcd GoldStar R420 gscd Note 4 Philips/LMS CM206 cm206 Note 5 Mitsumi CRMC LU005S mcd/mcdx Note 6, 7 Mitsumi FX001 m cd/mcdx Note 6, 7 Optics Storage Dolphin 8000AT optcd Lasermate CR328A optcd Sanyo H94A sjcd various various isp16 Note 8 Notes: 1.These drives may be sold under the names Creative Labs, Panasonic, Matsushita, or Kotobuki. 2.This drive is the same as a Panasonic CR-562. 3.May also be sold under the Procomm name. 4.May also be sold as part of a Reveal Multimedia Kit. 5.The Philips CM205 is not supported by this driver, but there is a separate alpha release driver available from ftp://sunsite.unc.edu in /pub/Linux/kernel/patches/cdrom/lmscd0.4.tar.gz 6.May also be sold under the Radio Shack name. 7.There are two drivers available. "mcd" is the original one, and "mcdx" is a newer driver with more features (but possibly less stable). 8.This driver works with CD-ROM drives that are attached to the interface on an ISP16, MAD16 or Mozart sound card. Above excerpt from LDP/Hardware HOWTO