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From: lindsay@k.gp.cs.cmu.edu (Donald Lindsay)
Newsgroups: comp.arch
Subject: Re: memory speed & futurology
Message-ID: <3162@pt.cs.cmu.edu>
Date: 29 Sep 88 03:46:14 GMT
References: <2179@ditmela.oz> <2220001@hpausla.HP.COM>
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In article <2220001@hpausla.HP.COM> cjh@hpausla.HP.COM (Clifford Heath) writes:
>>	It would seem that the access time on hard or optical disks is
>>	limited by rotational speed in the long run.
>Given the (perhaps almost) unlimited density of optical disks, the
>limiting factor on rotational speed is the speed of the encoder/decoder.
>If you want to spin a disk with 1 million bits/track at 1000
>revs/second, you've got to detect that information at 1Gbit/second.

I would say (from under my futurology hat) that it's basically silly to
have moving objects. We want to scan read/write beam[s] across unmoving
media. Of course, a disc is an inefficient shape: a rectangle has more
area. Also, it can't be too small, or people will lose them. I'd say that a
credit card has field-tested human factors. It would have to hold at least
a gigabyte, since we wouldn't want to split encyclopedias onto two cards.
-- 
Don		lindsay@k.gp.cs.cmu.edu    CMU Computer Science