Path: utzoo!utgpu!watserv1!watmath!att!dptg!lzsc!hcj
From: hcj@lzsc.ATT.COM (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: ATARI CDAR504 CD ROM PLAYER
Keywords: CDAR504 CD-Rom Player
Message-ID: <1956@lzsc.ATT.COM>
Date: 5 Jul 90 17:38:16 GMT
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 84



Notes on the CDAR504.

Since the only traffic dealing with the CDAR504 I have seen is my own, 
I may be speaking in a vacuum.  Nevertheless, here are my observations.

ATARI has made the CDAR504 available to DEVELOPERS at a very reasonable
price.  Further, there is evidence of plans to release a demo CD of 
ATARI software, which implies that sometime dealers will have CD players
to use.  And Sell?

I bought one of these beasties, to see what it would do.

1. I tried it on a Music CD.  The CDAR504 plays them.  There is even a
	DA to allow cataloging the tracks of multiple CD's.  NEAT!

2. There are no native ATARI CD's yet.  (Or least, I don't have access
	to one).  So no comment on their use.

3. There are lots of MS/DOS Data CD's.  I got hold of two that are intended
	for IBM PC's using the Microsoft CD Rom Extensions (MSCDEX).
	
	The CDAR504 comes with software that functions similarly to MSCDEX
	which allows trapping all the GEM OS calls the access files and
	permits doing it the mscdex way.  (Remember we have file systems
	of == 600 million bytes; far exceeding the gem/ms-dos limits of
	32 million bytes).

	The CD's may be opened from the desktop and files accessed, read,
	copied, and the like, without limitation.  Of course it is hard
	to copy a file of 200 million bytes to something else.  The real
	problem is that most of the data is compressed and is meant to be
	read with a program supplied in the directory structure of the 
	CD rom.  If the program had been native for an ATARI it would 
	surely work.  Unfortunately, the programs are for IBM PC's.

4. I modified PC-Ditto I (a true emulator) to interface to MSCDEX and 
	permit accessing the CDAR504.  Now I can access the whole disk
	and display the encoded information.  It is copyable also.
	
5. Next I got an Apple demo CD.  This is a true multi-media (nice buzz
	word, right!) disk.  It has 5 tracks on it, tracks 2 and 3 are
	speeches describing how great the CD is.  These tracks play on
	my Sony CD player; NOT on the CDAR504.  TROUBLE here!!

	When I try use the CDAR504 to read the contents of the data tracks
	it refused.

Problems with a CDAR504.

1. It turns out that this device internally will access only 2 types of
	CD rom data structure:
	A. Music.  The magic code is MUSIC, and multiple tracks may be 
		specified.  This can be played, but the binary read commands
		are disallowed.  No looking at the bits!!.
	B. Data.   The magic code is DATA.  A MSCDEX compatible CD then
		describes 1 track (containing the whole disk).  This can be
		read, but not played as music.

2. A Multimedia CD (as Apple does it) is structured as:
	A.  The magic code is DATA, but multiple tracks are specified.
		Think of this as the same as the partitioning of a Hard
		Disk.  The tracks serve to give Start and Extent, not
		Content.

	The CDAR504 handles this disk by allowing reads of track 1, and
	blocking access to the other tracks.

A Conclusion.

I bought the CDAR504 knowing only that it would play music, and read a 
yet to be produced Atari CD-rom.  I found that it will read and support
the common CD-roms for the IBM PC using the MSCDEX software.  Finally
I found that it will not read  multi track data cd's which I suspect
covers most of the multimedia ones that combine voice and data.

Hopefully, ATARI will see this and consider potential changes in their
CDARxxx product line if it is ever released.

Howard C. Johnson
ATT Bell Labs
att!lzsc!hcj
hcj@lzsc.att.com