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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