tim@gumby.cs.caltech.edu (Timothy L. Kay) (12/13/90)
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
usenet@bellcore.bellcore.com (Poster of News) (12/13/90)
tim@gumby.cs.caltech.edu (Timothy L. Kay) writes: >... My question is, do CD ROM drives conform to some >common command set? For example, are they simply treated as regular >disk drives? .... >Tim The CD ROM specification is defined, but experience says the drives aren't all compatible; I played with the Sun CD ROM and the drive doesn't seem to follow the SCSI 2 standard on CD ROM devices (section 13; dated 6/89). I couldn't get the Table of Contents instruction to work, although I know the drive can return such data since it is described in the Sun documentation. I believe Sun had SONY modify the internal drive microcode to fit their mold ofdevice drivers. Has anyone tried any other devices, or found similar experiences? I am waiting for the specs on the DEC drive. Are there other units available? Marc Pucci marc@bellcore.com Bellcore Morristown, NJ
gibson@b11.ingr.com (Stan Gibson) (12/15/90)
In article <tim.661021443@gumby.cs.caltech.edu> tim@gumby.cs.caltech.edu (Timothy L. Kay) writes: > My question is, do CD ROM drives conform to some >common command set? For example, are they simply treated as regular >disk drives? > I have tested CDROM drives from 5~6 different vendors. They all respond to the same read command. There are some vendor unique commands. Audio commands were not standardized until SCSI II so many vendors have unique command sets for their audio functions. Some vendors use unique mode select/sense pages to alter/report their buffer configuration but you don't have to use those. Also be aware that not every vendor uses the same caddy. Most use the "Sony" type, at least one uses a variation of the sony and LMSI has their own design. As I recall their users manual had eight pages showing how to load the caddy.
neese@adaptx1.UUCP (12/15/90)
>/* ---------- "Are CD ROM drives interchangeable?" ---------- */ >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? The basic answer to your question is NO, they are not compatible. The basic problem lies in the AUDIO command. There are some other subtle differences as well. This all stems from the fact that the SCSI-1 spec did not address CD-ROMS. The SCSI-2 spec does address these devices. SO the bottom line is: once all the CD-ROM guys get thier SCSI-2 devices out, the world will be a much happier place (or at least in this particular area anyway). So far as I know, Sony is the only one who has released a CD-ROM based on the SCSI-2 spec. Roy Neese Adaptec Senior SCSI Applications Engineer UUCP @ neese@adaptex uunet!cs.utexas.edu!utacfd! {nominil,merch,cpe}!adaptex!neese uunet!mlite!adaptex!neese
mannyn@cpqhou.uucp (Manny Novoa) (12/15/90)
In article <tim.661021443@gumby.cs.caltech.edu> 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
chuckl@chips.com (Chuck Linsley) (12/21/90)
In article <283400020@adaptx1> neese@adaptx1.UUCP writes: > >>/* ---------- "Are CD ROM drives interchangeable?" ---------- */ >So far as I know, Sony is the only one who has released a CD-ROM based >on the SCSI-2 spec. > Sony _claims_ SCSI-2 compliance, but it ain't necessarily so. The drive we have has some interesting non-compliant "features." For example, it ignores SDTR messages. It doesn't reject them, it just ignores them. Chuck Linsley chuckl@chips.com Mass Storage Operation Chips and Technologies, Inc.
tt@thor.acc.Virginia.EDU (Tang Tang) (12/22/90)
In article <1615@news.chips.com> chuckl@chips.com (Chuck Linsley) writes: >In article <283400020@adaptx1> neese@adaptx1.UUCP writes: >> >>>/* ---------- "Are CD ROM drives interchangeable?" ---------- */ >>So far as I know, Sony is the only one who has released a CD-ROM based >>on the SCSI-2 spec. >> > >Sony _claims_ SCSI-2 compliance, but it ain't necessarily so. The >drive we have has some interesting non-compliant "features." For >example, it ignores SDTR messages. It doesn't reject them, it just >ignores them. > Which sony drive are we talking about? I just bought a sony drive from DAK, model CDU-6201. It has a miniature 40 pins centronics connector. Does anyone know whether this is a SCSI drive. If so, what would you need to get it to work with a Mac? Where can I get a copy of the technical manual for the above drive. Thanks in advance, Tang Tang Academic Computing Center, University of Virginia.
gibson@b11.ingr.com (Stanley) (12/29/90)
In article <1990Dec21.191837.5048@murdoch.acc.Virginia.EDU> tt@thor.acc.Virginia.EDU (Tang Tang) writes: > > Which sony drive are we talking about? I just bought a sony drive from >DAK, model CDU-6201. It has a miniature 40 pins centronics connector. >Does anyone know whether this is a SCSI drive. The interface on your drive may be what Sony calls their "Sony Bus". It is their proprietary bus and would require their Host Adapter.