Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!brunix!rca
From: rca@cs.brown.edu (Ronald C.F. Antony)
Newsgroups: comp.sys.next
Subject: Re: What do I want to see in the Apple of the 90's?
Message-ID: <23181@brunix.UUCP>
Date: 18 Dec 89 01:45:19 GMT
References: <22438@ut-emx.UUCP> <3333@hub.UUCP> <1989Dec17.064813.16650@nueces.cactus.org> <37341@apple.Apple.COM> <9400@spool.cs.wisc.edu>
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Reply-To: rca@cs.brown.edu (Ronald C.F. Antony)
Organization: Brown University Department of Computer Science
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>NeXT is 2-bit GREYSCALE

If you take into account the alpha value (compositing) then it
is actually 4-bit, isn't it?

>Anyone who says 90 ms seek time isn't slow is lying or brain-dead.

I would't say it is fast, but the 90 ms don't tell the whole story.
a) within a certain range the access is much faster than one
would think, as it can be done by just moving the laser and not
the r/w head. (This can not be done with hard drives obviously)
Therefore the difference between avg.access (90ms) and track
to track access in a limited range is much bigger than with
pure magnetic media.
(I think within 5Mb the acces is something like 4-5 ms)
If you compare this to a e.g. 40mb hard disk, this an 8th of the
whole capacity. If such a HD had an avg. access time of 25ms
this would mean about a worst access time of 90ms and a track
to track access time of 4-5ms. If the HD has about 512 tracks, 
then it can access only 250kb of data within this time.
(250 kb are approx. the content of 3 cyl. of this 40mb drive)
b) the data transfer rate is pretty high
c) again: the optical should be considered as a floppy replacement, 
that's why there is no floppy in the NeXT. If you like the idea
or not, this is what it is meant to be. If you think the media is
too expensive: the 1.44MB floppies did cost more than 7$ when they
came out. So 15 times more money for 170 times the capacity
seems to be a good deal to me.

Ronald
------------------------------------------------------------------------------
"The reasonable man adapts himself to the world; the unreasonable one persists
in trying to adapt the world to himself. Therefore all progress depends on the
unreasonable man." - Bernhard Shaw | rca@cs.brown.edu or antony@cogsci.bitnet