Re: Which CD-ROM?

[stever@news.gate.net (Steve Reeves)]

In article <D0KMKw.660@actrix.gen.nz>,
David Empson <dempson@atlantis.actrix.gen.nz> wrote:
>In article <787000000.5993@myrias.ab.ca>, Devin Reade <gdr@myrias.ab.ca> wrote:
>> So what is the significance of the following terms (in the context
>> of CD ROM drives), and why would I want one feature vs another?
>> 
>> 	single speed   vs double (multi?) speed
>
>This one is easy - the speed of the CD-ROM drive.  The big question
>(which I've never known the answer to) is whether it refers to the
>data transfer speed, the seek speed, or both.

David, just the data transfer speed.  Single speed (the required speed for
playback of audio CDs) is 150 KB/sec, while double speed is 300 KB/sec.
Seek speeds of different drives can (and do) vary.

Devin, the data on audio CDs must be read at 150 KB/sec to play without
distortion.  Computer data on CD-ROMs isn't constrained in this way
(the faster its read, the better).  Multi-speed CD-ROM drives can read
the computer data at a higher speed (2x, 3x or 4x 150 KB/sec), while still
being able to step down to the slower speed to play audio data.  Single
speed drives have to read both kinds of data at the same slow speed.  So
multi-speed drives are preferable.

>To double the data transfer speed, the CD-ROM would need to spin twice
>as fast.
>
>I have also heard of triple speed and quadruple speed drives.
>
>> 	single spin    vs double (multi?) spin
>
>I don't know what this means.

These are generally synonymous with single speed and double speed 
(you explained why above: double the data transfer speed, double the spin
rate).

>> 	single session vs double (multi?) session
>
>This only applies when using writeable CD-ROMs, i.e. CD-R (recordable)
[correct explanation deleted]

These terms usually refer specifically to Kodak Photo CD discs (a special
case of CD-R).  Multi-session drives are preferable.

-- 
Steve Reeves
stever@gate.net