#CD Formats
8 messages in this thread
We distribute a graphical parts lookup program on CD-ROM's in ISO format, and a
new potential customer of ours has an installed base of old High Sierra drives.
Can new ISO drives (like the cheap Mitsumis) read High Sierra format disks? Can
old High Sierra drives (circa 1985) be upgraded to read new ISO format disks
(with a software or firmware patch maybe)?
The end-users will need to be able to switch between either kind of disk with a
minimum of fuss, as this is a parts counter type application. Or, will we have
to force them to upgrade their cd readers if they want to access any of the
other manufacturer's cd's with our database?
Thanks in advance, David.
I got a hold of a High Sierra disk and answered my own question about whether
new players could read old disks (yes), but can anyone tell me how much fits on
a High Sierra disk vs. an ISO disk?
Any suggestions about how to do this stuff will be welcome.
Thanks, David.
The amount of data that can be stored on the disc is due to the physical
mechanism of the drive itself. The older models are are 540 and the newer ones
that are currently available are 680 megs or so.
High Sierra (1986) is just a filesystem just like DOS. In older version of
MSCDEX it can only read High Sierra but not it also reads ISO. ISO-9960 oops
ISO-9660) (1988) is the sucessor to the High Sierra. The differences are very
minor so they shouldn't affect how much data can be stored on a disc.
Albert,
Thanks for your reply . . . but I'm not sure that I followed your answer 100%.
I understand that High Sierra is just a filesystem, but is the version of
mscdex.exe the only deciding factor of whether or not a given drive can read
ISO format discs? Are there no hardware issues?
For example, If I want to send a ISO-9660 disc to someone with an old cd reader
(circa 1985) that's never seen anything but a High Sierra disc, can he just
replace his mscdex.exe with a newer one and have no problems?
Thanks again, David.
David,
ISO-9660 and High Sierra are both filesystems. Changing the MSCDEX to the most
current one should work without any problems.
If the drive is from 1985 it may be possible that the driver used for the
CD-ROM drive might not like the newer version of MSCDEX v2.2x.
The best thing would be to upgrade the version of MSCDEX that the person is
using and see if it works with the cd-rom driver. MSCDEX is just the interface
between the cd-rom filesystem (ISO or High Sierra) and MS-DOS by the way.
It the ISO-9660 disc is not greater than 540 megabytes it should work assuming
the driver works with a newer version of MSCDEX.
Since the logical boot sector on a CD-ROM is 16 the program may run fine until
it has to access any data greater than 540 megabyte limit. How much data is on
your ISO-9660 disc?
Albert,
So, if I understand you correctly, you're saying that for:
hardware – there is nothing to worry about other than the amount of
data on the disc (a 540 meg limit is not a problem, as
our current discs have less than 400 meg)
software – IF the old device drivers get along with a new version of
the mscdex redirector (won't know until we try), there
should be no problem as long as we don't go over the 540
meg limit. Any ideas about the odds of the device driver
and a new mscdex getting along?
Thanks, David.
David,
You got it right perfectly. Odds on driver compatibility with MSCDEX very
greatly. You there are a couple 2.x versions floating around so you can try
all of them 2.0, 2.1 and 2.2 are the versions out there.
What version of DOS is the person running? Some versions of MSCDEX might only
work on newer versions of DOS mainly 5.0 or higher.
The best thing is to try something of course. Make sure the person has backups
of the software drivers and the version of the MSCDEX he/she is currently using
too. Just o be on the safe side.
Hi David,
as the MSCDEX specification includes the interface to the low-lewel device
driver for the CD-ROM drive you should also upgrade this device driver to work
with MSCDEX 2.X (Version 1.X supports High Sierra only).
Bye, Torsten