Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cpqhou!mannyn From: mannyn@cpqhou.uucp (Manny Novoa) Newsgroups: comp.periphs.scsi Subject: Re: Are CD ROM drives interchangeable? Message-ID: <1990Dec14.203556.1825@cpqhou.uucp> Date: 14 Dec 90 20:35:56 GMT References: Reply-To: mannyn@cpqhou.UUCP (Manny Novoa) Organization: Compaq Computer Corporation Lines: 38 In article tim@gumby.cs.caltech.edu (Timothy L. Kay) writes: >I can buy hard drives from many manufacturers. My SCSI driver on my >workstation seems to be able to handle most of them. The same goes >for tape drives. My question is, do CD ROM drives conform to some >common command set? For example, are they simply treated as regular >disk drives? (Obviously, there needs to be a special driver to >understand the ISO9660 format, but can they share code with the >regular disk drivers?) Or do CD ROM manufactures each use their own >set of commands? > >Thanks in advance, > >Tim Tim, Good news for you!!! It is possible (and I mean only POSSIBLE) to have a SINGLE driver to talk to CD-ROMs from different manufacturers. This is true, if the CD-ROM drive implements the "common" command set from the SCSI-2 specification for CD-ROM devices. Some drives that implement this are SONY-541 and Toshiba XM3301 (there's probably others too....!) Note that even before the SCSI-2 "standardization" of the CD-ROM command set, it was possible to read data from different manufacturers CD-ROMs. Problem is that they each had different audio commands, etc.... Now, as most of the CD-ROM vendors move to be SCSI-2 compatible, you'll find that the drives implement the "SCSI-2" command set as well as their "older" vendor-unique commands. Also note that the majority of commands for any device class under the SCSI-2 specification are OPTIONAL. So, if what you want to do with a device is classified as a required command, then you're in business with a single driver for multiple vendors' product. If you need to use the optional commands, then you'll have to search for a while to find "compatible" devices. Hope this sheds some light on the situation. I have used both of the devices mentioned above with a single driver.....(you're mileage may vary..!) Manny.... ____________________ Compaq Computer Corporation mannyn@cpqhou.uucp