Astronomical Data Center
Q & A on the Selected Astronomical Catalogs, Volume 4 CD-ROM
Since the ADC discovered that the original production run of the ADC CD-ROM Selected Astronomical Catalogs,
Volume 4 won't work with computers running certain operating systems, we've received many questions
from users trying to better understand what this means. This page contains key details
that explain the situation.
Q: Why did you make the new ADC CD-ROM incompatible with some operating systems?
A: We fully intended to make it in conformance with ISO 9660. The problem that is present was
not intentional.
Q: Will I be able to use the CD-ROM on my UNIX (or LINUX) system?
A: While we haven't tested it under all varieties of UNIX, we have been able to read it
on systems running DEC UNIX, Sun Solaris, and SGI IRIX operating systems. The lower case
file names should be no problem for any flavor of UNIX.
Q: Will I be able to use it on my Macintosh computer?
A: Yes.
Q: Will I be able to use it on my Windows NT computer?
A: We have found that it may not be compatible with Windows NT v. 3.51. It appears to
work fine with Windows NT 4.0. If the system is using the older MSCDEX CD-ROM real-mode driver, it
will not work. If it is running the CDFS CD-ROM driver, we believe it should work.
Q: How is Selected Astronomical Catalogs, Volume 4 incompatible with MS Windows 3.x and DOS 6.x?
A: All the directory and file names on the CD-ROM are composed of lower case letters. This
appears to make it impossible to navigate the directories or read the files on computers running those
operating systems. This seems to depend on the CD-ROM driver in use by the system - not the operating
system per se. The driver controls the file I/O from the CD-ROM drive. MS Windows 3.x and DOS 6.x
typically use a driver called MSCDEX. Systems using this driver have the problem. Windows 95 and NT
use a driver called CDFS. CDFS appears to handle the lower case letter names without problems.
Q: How did that happen?
A: The software that was used to create the pre-master CD-R for the new ADC
CD-ROM is Toast CD-ROM Pro 2.5.6 for Macintosh by Astarte. This software
offers a number of options when building an "ISO 9660" image to be written to
CD-R. As best we can determine after the fact, it appears that one of these
options, "Allow Macintosh Names", was selected without a full understanding
of what effect it would have.
The files and directories were originally set up on a DEC UNIX workstation.
While we made a point of limiting the file names to 8 by 3 characters in length,
we did not convert them to uppercase on the DEC. The CD-R authoring software
can do that conversion automatically when preparing the ISO 9660 image.
The problem comes from a feature of this "allow Macintosh names" option. We
now realize that it turns off the automatic name conversion. If the input
file and directory names don't already conform to the ISO 9660 Level 1
standard, the resulting names won't either.
Q: Why didn't you see the problem on the CD-R premaster disc before producing
the CD-ROMs?
A: During our checkout of the CD-R premaster, prior to production of the CD-ROM,
we tested it under Win 95, DOS (as included with Win 95), DEC Unix, and Mac
OS. None of these had problems reading the disc. Since we did not have a system
running Win 3.x at hand, we didn't test it on such a system. We assumed that if it looked
OK from DOS on a Win 95 machine, it would be OK under DOS 6.x . We now know
that that is not always true.
Q: How is the ADC dealing with this problem?
A: We have produced a new release of 500 new Volume 4 CD-ROMs which have been
mastered to strict ISO 9660 level 1. These are now available for those who might encounter problems
using the first release discs. If you need the new disc, please specify Volume 4, Release 2 when
requesting this CD-ROM. If you've already received a Volume 4 CD-ROM and cannot use it because of the
file name problem, please contact us
at ccheung@adc.astro.umd.edu.
The Astronomical Data Center