[comp.sys.mac.hardware] Can you use an Audio CD as a CD ROM?

david@oahu.uucp (01/20/90)

I have a Sony CD player (audio) and it has this multi-pin connector in the
back called "Subcode out."  The manual mentions using it for connecting to
"future equipment."  Can this be used to hook up to a Mac?



David Dantowitz
david@cs.ucla.edu

Singing Barbershop when I'm not computing...

blob@apple.com (Brian Bechtel) (01/22/90)

In article <31064@shemp.CS.UCLA.EDU> david@oahu.uucp writes:
> I have a Sony CD player (audio) and it has this multi-pin connector in 
> the back called "Subcode out."  The manual mentions using it for 
> connecting to "future equipment."  Can this be used to hook up to 
> a Mac?

Both audio CDs and CD-ROMs are encoded using the same standard.  CDs have 
eight subcoding channels labeled P through W which contain some 
information.  Subtrack P contains a simple music track separator.  Channel 
Q contains control information such as track number, track type, and 
location (minutes, seconds, frames).  During the lead-in track, channel Q 
contains table of contents information for the disc, with track number and 
starting location of each track.

The other six channels aren't used in any standard way; there have been 
some proposed standards that these tracks include labelling information 
(e.g. track name) or graphics (e.g. the CD-Graphics standard Sony is 
trying to promulgate.)  This "Subcode out" connector is probably meant to 
allow access to all eight subcodes so that graphics, text, etc. could be 
processed by an external component.

Notice this all has nothing to do with an external device taking control 
of a CD.  If you want this, you need a CD-ROM drive, not (most) audio CD 
drives.  This is "subcode out", not "commands in".

--Brian Bechtel     blob@apple.com     "My opinion, not Apple's"