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Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!tgr!vortex!lauren@RAND-UNIX.ARPA
From: lauren@RAND-UNIX.ARPA
Newsgroups: net.micro
Subject: CD-ROM speeds
Message-ID: <145@brl-tgr.ARPA>
Date: Wed, 24-Jul-85 13:55:40 EDT
Article-I.D.: brl-tgr.145
Posted: Wed Jul 24 13:55:40 1985
Date-Received: Fri, 26-Jul-85 03:03:16 EDT
Sender: news@brl-tgr.ARPA
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There is certainly work going on at trying to speed them up (particularly
the NEWEST consumer models, since people have been bitching) but the
exact seek times will still depend heavily on TOC contents.  With some
contents, you can run in what's called "high-speed-kick" mode throughout
the search.  With some you can't, and you end up approaching the worst
case situation--which presumably is what we're most concerned with.
Of course, you indeed COULD put multiple lasers in the thing and multiple
head assemblies if you're willing to pay enough for them--presumably
some fanatic will insist on doing this at some point.

Note that a typical popular music CD is little more than half as long
(if that) as the disk capacity.  Few discs (comparatively) run over
an hour (manufacturing costs go up past 60 minutes).  For typical
length discs (even regardless of exact TOC timing which affects
whether you can use slow or high speed kick during any particular
search) there's a lot of excess capacity with which you need
not deal (equiv. of having a "narrow band" of data).  Classical music
discs with only a few bands may be longer, but the lack of dense
banding allows for faster access through precalculated high speed
searches.

--Lauren--