Re: separate data/inidex

In article <1019891456.25305.1.nnrp-13.9e984b29_at_news.demon.co.uk>, you said (and I quote):
>
> The thing that puzzles me about this point is
> why no-one has come onto the market with
> a drive that holds multiple sets of heads,
> say every 90 degrees (pi/2 radians) around
> the disc. Expensive, no doubt, but cuts
> the rotational latency by a factor which would
> probably get close to 4 (given the right s/w
> and a mechanism for synching the position
> of the disc.
>

They DID exist. Both IBM and Sperry at the very least had a model of removable drive with multiple radial head sets. They were called disk/drums, due to the response similarity with the old magnetic drum devices. In fact, IIRC Sperry once sold one that had multiple heads around the bottom platter which could read a sector in much less than a full rotation. Can't remember the model number, this was ages ago.

With current technology at least two head movements would be dirt easy to do. More, I dunno. There isn't just enough space in small modern disk drives for the actuators. Of course, the trick would be to make them very small, one per cylinder and static. Dunno if anyone is looking into this.

-- 
Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam