From: (Neil Wagner) - CED Magic

promised to continue production into 1987, though they stopped in 1986."
My understanding is that RCA *was* manufacturing discs in 1987; the last
major new title apparently was "Back To The Future." Also, the reporters
who cover the consumer electronics industry -- several of whom I know fairly
well -- were pretty much in agreement that RCA was *losing* money overall on
CED, not merely missing their return-on-investment targets; they were
selling the players below cost in order to build a customer base for discs,
but didn't do enough of that to recoup their losses.
--
Ed Ellers
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Date: Sun, 19 Oct 1997 15:00:29 -0500
From: Geoff Oltmans
MIME-Version: 1.0
To: Tom Howe
Subject: Re: CED Digest Vol. 2 No. 42
Dave wrote:
> So why does the CED have to spin so fast??? Why couldn't they have
> just pressed them at 33 and 1/3 rpm or something slower??? I'm just
> curious.....
>
The CED really doesn't spin THAT fast. Comparitively speaking, the
floppy disk drive spins at 300 RPM, and the Laserdisc spins at a max of
around 1800 RPM.
There are a few reasons that the discs spin at 450 RPM. Firstly, if the
disc were to spin too slowly, for example, the 33 1/3 RPM like you
mentioned, the information would be packed too densely and the
information couldn't be extracted back off of the disc.
Here's a little math :)
The CED media has the following characteristics:
Each revolution contains 4 complete frames of video (as well as sound)
If you look at the disk you can see this fact because the disk is
subdivided into 8 sectors (NTSC is an interlaced format, so two sectors
are required to make a single frame).
CED's are approximately 12 inches in diameter
approx " of this is actual recording media.
CED's have 9500 grooves per inch
Okay, now if we keep this in mind ~3.25" x 9500 (note: we use 3.25"