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From: neal@weitek.UUCP (Neal Bedard)
Newsgroups: net.periphs
Subject: Re: streamer tapes
Message-ID: <339@weitek.UUCP>
Date: Mon, 9-Dec-85 18:06:11 EST
Article-I.D.: weitek.339
Posted: Mon Dec  9 18:06:11 1985
Date-Received: Wed, 11-Dec-85 21:51:49 EST
References: <91@calma.UUCP>
Organization: Weitek Corporation, Sunnyvale
Lines: 28

In article <91@calma.UUCP>, radzy@calma.UUCP (Tim Radzykewycz) writes:
> 
> For those of you with a little curiosity:  Why do that?  The
> reason is quite simple.  If you don't have to worry about changing
> from 100 ips to a standstill in less than 1/4 inch, then you
> can easily use *much* cheaper drive motors.  The electronics
> design does get a little tougher, though, because of the ramp-up/
> rewind/ramp-down, but that is insignificant compared to the drive
> motors.

Though they need to be high torque and low inertia, the motors themselves
aren't terribly expensive (that particular industry is quite competitive,
with many Japanese vendors.)

The encoders, drivers (usually *big* switch-mode transistors, sometimes
linear-mode), DAC's, velocity profile generators (usually microprocessors
these days, sometimes bit-slice or a combination thereof), high-current
power supply, etc. can add up to some bucks.

One approach to get around this is to provide a cache inside the tape drive,
as is done in the Cipher CacheTape, a front-loading 9-track streamer drive
that is purported to behave like a start-stop unit. I personally don't know
how well the CacheTape works, though I've heard good things about it.

-Neal
-- 
55. It's a law we can do away with.
UUCP: {turtlevax, resonex, cae780}!weitek!neal