Clarification on CD-DA bit of Mode Page 2A hex
worrell at dt.wdc.com
Tue Jan 27 11:06:58 PST 1998
* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* Devon Worrell <worrell at dt.wdc.com>
Here is my two cents worth (maybe only 1.5 cents). The only command
that has been "Standardized" is the READ CD command. The READ CD-DA
command does not exist except in some SCSI drives. I know that Sony
has had this command for some time, but it did not make it into
the standard, thus the bits must refer to the standard in which they
The CD-DA support refers to JUST the READ CD and READ CD MSF commands,
which both must be supported. If the drive can find the same data
twice then the ACCURATE bit can also be set. Note that in the future
with MtFuji-2, MtFuji-3 and MMC-2 (Assumed) that the READ CD and the
ACCURATE bits are both mandatory.
Perhaps the name/wording could be changed to indicate that a drive that
reports 0 in the CD-DA Commands Supported bit may support audio reading,
but not using the READ CD command. e.g. Byte 5, Bit 0, AudioRead, if
this bit is set to 1, the logical unit shall be capable of reading Audio
Sectors when the READ CD and READ CD MSF commands specify returning 2352
bytes of data with an audio sector address.
At 9:33 AM -0800 1/27/98, Dennis Pak wrote:
>To MMC members,
>I would like to get a clarification on the CD-DA supported bits (Byte 5,
>bits 0 and 1) of
>CD Capabilities and Mechanical Status Page (2A hex).
>Here is the current description:
>Byte 5, Bit 0, CD-DA Commands Supported, audio can be read using the
>READ CD command.
>Byte 5, Bit 1, CD-DA Stream is Accurate, indicates that the drive
>supports an advanced
>feature that allows it to return to an audio location without losing
>place to continue the
>READ CD command.
>The fundamental question is 'should the bits 0 and 1 be set if the
>features are supported,
>but without the READ CD command support?' For instance, the CD-DA
>support is provided via
>the 'READ CD-DA' command.
>Your clarification on this matter would be appreciated.
_/_/_/_/ _/_/_/_/ _/ _/ | Devon B. Worrell <worrell at dt.wdc.com>
_/ _/ _/ _/ _/ _/ | Senior Staff Engineer
_/ _/ _/_/_/_/ _/ _/ _/ | Interface Technology
_/ _/ _/ _/ _/_/_/_/_/ | Western Digital Corporation
/_/_/_/ _/_/_/_/_/ _/ _/ | 8105 Irvine Center Dr
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