Date: Fri, 3 Apr 1998 12:01:48 GMT
From: pete@dunnington.u-net.com (Pete Turnbull)
Message-Id: <9804031301.ZM14090@indy.dunnington.york.ac.uk>
In-Reply-To: "Ed G." <edgee@cyberpass.net>
        "Re: What's magtape good for anyway?" (Apr  2, 22:15)
References: <199804030315.WAA06617@renoir.op.net>
Reply-To: pete@dunnington.u-net.com
To: pups@minnie.cs.adfa.oz.au
Subject: Re: What's magtape good for anyway?
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 8bit
Sender: owner-pups@minnie.cs.adfa.oz.au
Precedence: bulk

On Apr 2, 22:15, Ed G. wrote:
> Subject: Re: What's magtape good for anyway?

> Was dectape an attempt to remedy some of these problems?  My
> hazy recollection was that you could treat dectape in some ways as if
> it were a disk.

Yes, in the sense that you could perform random-access operations on it.  I
used a PDP-8 that had twin DECtape instead of disks.  It supported 4(?)
teletypes in a multi-user environment.  But DECtape was not 1/2" tape, nor did
it use reels like the ones that later became standard.

> How much data can magtape hold?  If magtape was a portable media,
> does that mean that the manufacturers agreed on the width of
> the tape, the density of recording, the method of recording bits,
> etc.?

Yes to all of those, though there are three standard recording densities
(80bpi, 1600bpi, 6250bpi) and several recording methods (NRZ, NRZI, PE, etc).
 There are different standard lengths too:  600' 1200' 2400'.

> I have an old 9 track tape from a computer course I took in 1980.
> For sentimental reasons I'd love to get a copy of its contents.  Is
> this possible do you think?

Shouldn't be hard, unless it's suffered from print-through after 18 years.
 It's probably 800bpi (NRZI) or 1600bpi (PE).  Whether you can understand the
contents depends on the format of the data, of course.


-- 

Pete						Peter Turnbull
						Dept. of Computer Science
						University of York