Tracking ATAPI CD-ROM Cmds in SCSI-3
Duncan Penman
penman at netcom.com
Wed Sep 21 21:56:36 PDT 1994
Currently the SCSI (-2 or -3) CD-ROM command set lags the ATAPI CD-ROM
command set in terms of support for recent CD-ROM features. The SCSI-3
MMC document is being updated, with the goal of making the SCSI-3
command set current.
Norm Harris, the editor, has ported over the following ATAPI commands:
AUDIO SCAN
PLAY CD-ROM XA
READ CD
READ CD MSF
SET CD-ROM SPEED
STOP PLAY/SCAN
I believe these are all reasonable additions to the SCSI-3 CD-ROM command
set.
In addition to the new commands listed above, I'd like to propose 3
other changes.
1. Update the READ TOC command to include a 2 bit Format field, mapped as
in the ATAPI version of the command. This extends READ TOC support to
multisession discs.
There are several Reserved areas in the current READ TOC CDB. A question
for the folks doing ATAPI BIOS or chip design...Is there any
CDB-to-Command-Packet mapping convention that would dictate a preference
for one location vs another for this new field in the CDB?
2. Add the ATAPI-defined CD-ROM Mode Page 2A, "CD-ROM Capabilities and
Mechanical Status Page". The Page Code assigned by ATAPI (2Ah) should be
reviewed. This is in the SCSI Vendor Unique range for Page Codes so it
may conflict with some existing usage. On the other hand, most of the
major CD-ROM manufacturs have reviewed and approved the ATAPI CD-ROM
specification so there may even be a precedent for this usage.
Again, can anyone shed some light here?
3. Add 5 ATAPI-defined Medium Type Codes. These are:
04 and 08 120mm and 80mm Photo CD, respectively
70 Door closed, no disc present
71 Door open
73 Door closed, medium format error
Note: see SFF8020 for exact wording.
I'm sure this is not an exhaustive list, just those items I've come up
with in reviewing Norm's latest rev of MMC. Anyone else care to add
something?
Duncan Penman
Zadian Technologies
penman at netcom.com
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