Re: audio discs on generic CD-ROM drive?

[dempson@swell.actrix.gen.nz (David Empson)]

In article <C4pvAF.Dw6@eskimo.com> lurch@eskimo.com (Erik Kloeppel) writes:
> dempson@swell.actrix.gen.nz (David Empson) writes:
> 
> >I'm not sure what happens if you put an audio CD into an Apple CD-ROM
> >drive (I'm using my borrowed drive on a IIe as a CD Player at the
> >moment, and haven't used it on the IIgs for a few months).
> 
> I don't know the specifics, but I think in laymans terms what happens is
> that when you put an audio disk in, the system tries to read it, sees
> that it's not in any recognizable data format and ignores it.  

I suspect that the CD-ROM driver sees that there is a disk in the
drive, but it has no accessible data blocks (you cannot read the audio
data from a CD through the SCSI interface).

> The CD REMOTE NDA probably looks for the correct formatting and pulls
> the data through the ensonic or something directly - essentially
> by-passing the processor. 

:-)

No, the Ensoniq and IIgs sound circuitry are not used at all.  CD
REMOTE sends a command to the CD-ROM drive which tells it to start
playing sound from a specified track and time offset.  The CD-ROM
drive plays the sound via its audio output - the computer has nothing
else to do other than monitor the progress (you can request the
current playback location, and mode of operation, for example).

> Granted - this is all a guess, but it's based on no education at all.  All
> I REALLY know about this is:  I put an audio disk in, the drive is scanned
> for a few seconds, then ignored (treated as essentially empty).  CD REMOTE
> scanns the disk, and starts the music.

I'll have a closer look in a couple of days - my CD player has been
fixed so I can put the CD-ROM drive back on the IIgs.
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz    <--- Note my new E-Mail address!            
Snail mail: P.O. Box 27-103, Wellington, New Zealand