From: scotty@gagetalker.com (Scott Turner)
Newsgroups: comp.sys.next.hardware
Subject: Re: Foreign CD-ROM disks on NeXT
Date: 11 Sep 92 06:56:12 GMT
Organization: L5 Computing

In article <92251.121431MKK2@psuvm.psu.edu> <MKK2@psuvm.psu.edu> writes:
|> I hope someone will fill in some gaps about CD-ROM for me and the rest of
|> this group.
|> 
|>   As I understand it, the ISO CD-ROM format is some kind of hierarchical
|> file system modeled after the one Unix offers (based on OS-9?).  I presume
|> that msdos, Mac, Unix, or NeXT must develop some kind of driver that  
translates
|> to and from that format.
|> 
|>   Does this mean the data files on a CD-ROM will be available to NeXT's file
|> viewer.  For example, will the Great Works of Literature on a GWOL disk
|> be readable?  I know that the *software* for reading them will be useless.   
I
|> am curious about the data.
The structure of an ISO-9660 CD-ROM has more in common with the extent based
filesystems in use on Cray super computers than it does with Unix or OS-9
filesystems (and no, the unix filesystem is _not_ based on os-9, it's the other
way around.)

Strictly speaking the NeXT computers speak a sub-set of ISO-9660, all the
filesystems supplied by NeXT have been found to be non-conforming on
many points.

This means that not all ISO-9660 discs work with the NeXT. Some in fact even
lockup the NeXT when it attempts to mount them (you then must manually eject
the disc and reboot.)

Some discs appear to work in that you can scan them, but when you actually
try to read files you'll get junk at the front of the files.

Even dates aren't sacred, don't go betting the farm on a date you get from a
NeXT about a file on an ISO-9660 CD-ROM, and come to think of it, the time
can be off as well.

But before this turns into a NeXT cashing article, I've used several Mac
ISO-9660 filesystems that have locked up as well.

The best ISO-9660 implementation I know of is MSCDEX.EXE for MS-DOS. This
appears to be a near letter perfect ISO-9660 filesystem implementation.

So to answer your question, it depends on the disc. You may be able to access
the data, or you may not be able to. You'll have to try it and see. I
personally have had success with many IBM PC titles (and if Soft PC will
ever do Win3.1 I'd have even more success.) Don't forget about SoftPC and
Executor, these products will sometimes allow you to use the machine specific
retrieval engines to get at the data on the discs.

And for those with Executor who have been eagerly awaiting 3.0 so that they
can access Mac CD-ROMs... There's a gotcha, the NeXT checks for ISO-9660
compliance before it checks for a Mac HFS. If you wanted to play with a disc
such as one the "Selectware" discs you'll find that the NeXT mounts the
ISO-9660 part of the disc, which contains only IBM PC software (which works
great with Soft PC BTW) you can't get at the Mac software on the disc.

So far I haven't been able to talk my NeXTs (one is not enough ;) into mounting
the Mac HFS part of the disc (it'll play "Please insert disc" "Wrong disc"
"Please insert disc" for as long as I care to play.)

Pure Mac HFS CD-ROMs do mount under 3.0.

Scotty
Newsgroups: comp.sys.next.hardware