X3T9.2/90-200

Date:          January 2, 1991

To:            X3T9.2 Committee (SCSI)

From:          Bob Simpson (Sony Corporation)

Subject:       CD-ROM Logical Block Address Clarification
               Sony proposal for SCSI-2 standard 


Problem:

The  current  model for CD-ROM devices does  not  clearly  define 
logical address zero of the first track on a Mixed Mode (audio  & 
data) CD-ROM disk.


Background:

If  the  first track is a data track, the  Yellow  Book  Standard 
specifies  that the starting address of the first track shall  be 
00 min 02 sec 00 frame.

If  the first track is an audio track, the RED Book format  (e.g. 
CD-Audio format) allows the starting address to be between 1  and 
3 sec.

Therefore, if a drive which sets 00 min 02 sec 00 frame to LBA  0 
is used with CD-Audio disc, the beginning of the first track  may 
be muted.



Proposal:

One  sentence  should be added on page 13-1  of  SCSI-2  standard 
Revision 10c.

The  sentence is indicated by Italics/Underline/Bold on  the  at-
tached page.







13. CD-ROM Devices

13.1. Model for CD-ROM Devices

  CD-ROM  devices permit reading data from a rotating media.  Writing the 
media  is not  supported.   Data  transfer can begin with any of  the  
consecutively  numbered logical  blocks.  Data on CD-ROM devices is addressed 
the same as  usual  (magnetic) direct-access  devices.  Some CD-ROM devices 
support a separate  information  stream (e.g. audio and/or video but referred 
to as audio in this section) transmitted via a connection  other than the SCSI 
Bus. This device type defines commands for  control- ling these other 
information streams. 

  CD-ROM  drives  are designed to work with any disc that meets the "Red  
Book"  or "Yellow  Book" (IEC 908) documents at the current revision level.  
Many  new  drives read  CD-ROM  data discs, digital audio discs, and audio-
combined discs  (i.e.  some tracks are audio, some tracks are data).

13.1.1. CD-ROM Media Organization

  The formats written on the CD-ROM and CD-DA (Digital Audio) media require 
special interfacing considerations. 

  NOTE: This section contains a number of terms which have special meanings  
pecul- iar to CD-ROM technology or that may be unfamiliar to many readers of 
this standard. The glossary (see 13.4.) defines these terms.

  These  discs may contain either audio, data or a mixture of the two.  Table  
13-2 shows the format of a audio-combined disc to illustrate the relationship 
between the logical  block addresses reported in SCSI and the MSF address 
encoded on the  media.  The logical address zero of the first track must be 
set to the absolute starting MSF address of the track reported by the TOC.

  NOTE:  The term frame is used in two different ways in the CD-ROM media 
  standard.  The intended meaning can only be determined from the context. 
  Whenever  possible, this  description  replaces  the larger data unit with  
  the  more  familiar  term "sector".   The primary exception to this policy 
  is the use of frame when  refer- ring to the MSF address.  In the MSF 
  context, one frame (F Field unit) equals one sector.   On  a  typical two 
  channel CD-DA media, each frame (F  Field  unit)  is played in 1/75th of a 
  second.