7 Sep
2010
7 Sep
'10
6:32 p.m.
What was the reason for the carriers used on first generation CD-ROM drives?
My first CD-ROM drive cost about $800, but it included an encyclopedia. :-)
It used the "standard carrier".
I have a Pinnacle RCD-1000 disk burner that also uses the same carrier. I
remember that it was attached to an IBM PC-AT or something close and that we
basically turned out the lights in the room so as not to disturb it during a
burn.
The audio drives used the drawer. I know the error correction is better on
the audio disk than the data disks, but I haven't found the data disks to be
that unreliable.
Anyway, why the carriers?
-chuck
11 Sep
11 Sep
12:02 p.m.
On Tue, Sep 07, 2010 at 06:32:36PM -0400, Charles Dickman wrote:
What was the reason for the carriers used on first
generation CD-ROM drives?
I guess the idea was to protect the media from damage, as data disks are
far more sensitive to errors than audio disk ("can't read file" versus
a short noise pulse).
My first CD-ROM drive cost about $800, but it included
an encyclopedia. :-)
It used the "standard carrier".
I have a Pinnacle RCD-1000 disk burner that also uses the same carrier. I
remember that it was attached to an IBM PC-AT or something close and that we
basically turned out the lights in the room so as not to disturb it during a
burn.
The audio drives used the drawer. I know the error correction is better on
the audio disk than the data disks,
It isn't. CD-ROMs add another layer of error correction on top of what is
already used for audio CDs, so the error correction for CD-ROMs is better.
However, audio CDs are far less troubled by errors - at worst, you'll hear
some annoying sound artefacts from the damaged sectors, whereas with a
CD-ROM data errors means that you can't read (parts of) the afflicted file
or directory.
Kind regards,
Alex.
--
"Opportunity is missed by most people because it is dressed in overalls and
looks like work." -- Thomas A. Edison
2:41 p.m.
Charles Dickman wrote:
I know the error correction is better on
the audio disk than the data disks,
Alexander Schreiber wrote:
It isn't. CD-ROMs add another layer of error
correction on top of what is
already used for audio CDs, so the error correction for CD-ROMs is
better.
Only for Yellow Book Mode 1 or Mode 2 form 1. Mode 2 form 2 does not
have L3 error correction. Admittedly Mode 2 is extremely rare now.
However, audio CDs are far less troubled by errors -
at worst, you'll
hear
some annoying sound artefacts from the damaged
sectors, whereas with a
CD-ROM data errors means that you can't read (parts of) the afflicted
file
or directory.
It's more complicated than that. While CD-Audio (Red Book) doesn't have
the L3 error correction of CDs, it does still have interleave, so
defects beyond the correction capability of the L1+L2 error correction
will almost never drop two consecutive samples. There may, however, be
runs in which every other sample is missing. In this case, the player
uses "error concealment" by interpolating between the samples to either
side of the missing one(s). This results in a momentary drop in the
audio bandwidth, but is usually not noticeable.
When there are errors that result in multiple consecutive lost samples,
the player will mute the audio, which was considered to be less
unpleasant than playing digital noise. However, when there are rapidly
alternating segments of good samples and multiple consecutive lost
samples, it can end up sounding like digital nose anyhow.
Eric
3:04 p.m.
New subject: Why CD carriers?
CD-ROMs were EXPENSIVE!
For years, the price of them was so high that institutional purchases
would typically dedicate an entire PC as a player for each one. (PCs were
more expensive then, also). In those days, I compared that practice to
buying a movie projector for each film purchased.
I remember buying a used CD-ROM play only drive for $300.
I remember when the first under $2000 writer (1X) came out. But, I didn't
buy one until they got down to $300. Mad a lot of coasters - the success
rate was under 25%
For many years, I lusted after a Qubik (sp?). That was a changer designed
by Keith Henson, that had a rotating carousel style tray holding 240?
CD-ROMs, mounted in a square box with from 1 to 4 drives in the corners.
(SCSI drive(s), RS232 control of the changer)
--
Grumpy Ol' Fred cisin at xenosoft.com
5059
days inactive
5063
days old
4 comments
4 participants
participants (4)
-
als＠thangorodrim.de -
chd＠chdickman.com -
cisin＠xenosoft.com -
eric＠brouhaha.com