28 Jun
2020
28 Jun
'20
5:15 p.m.
Also FWIW 3M Types 108, 109, 128 and 159 were advertised in 1958 as ?instrumentation
tapes? used for ?critical recording work? on ?? computers ??
From: Tom Gardner [mailto:t.gardner at computer.org]
Sent: Sunday, June 28, 2020 5:08 PM
To: 'Paul Koning'; 'cctalk at classiccmp.org'
Subject: RE: Early 3M Computer Tape Type Numbers
FWIW this is an announcement of a 3M brochure from a 1957 Datamation:
Magnetic Tape for Instrumentation, an 8-page brochure, covers six types of
"Scotch" brand instrumentation tapes for use in telemetering and airborne
recording, machine tool control systems, computers, geophysical recording, and other
instrumentation applications. Included are charts listing physical and magnetic properties
of each of the precision tapes and a comparison chart summary of major factors in
selecting a tape for a particular application.
Minnesota Mining & Mfg. Co., 900 Bush St., St. Paul 6, Minn.
Circle 113 on Reader Service Card
Apparently 3M ?Instrumentation tapes? can be used for ?computers?
AFAIK 3M early ?Instrumentation tape? types include Type 148/149 and Type 480/481 but both
were announced after the 1957 brochure mentioned above
It looks like all 3M ?Type? tapes of this early era were available in a variety of widths,
from ?-inch to 2 inches
-----Original Message-----
From: Paul Koning [mailto:paulkoning at comcast.net]
Sent: Friday, June 26, 2020 11:44 AM
To: Tom Gardner
Cc: cctalk at classiccmp.org <mailto:cctalk at classiccmp.org Subject: Re: Early 3M Computer Tape Type
Numbers
On Jun 26, 2020, at 1:46 PM, Tom Gardner <
<mailto:t.gardner at computer.org> t.gardner at computer.org> wrote:
Paul
Thanks, I had found this ad a while ago but thought it
was ?-inch. Upon careful reading all the notes I found, "Errors per roll based on
recording 7 tracks on rolls ?" x 2500'. "
It looks like 3M may have called their computer tapes
"Instrumentation" tape until the late 60s
Tom
"Instrumentation tape" sounds like a reference to instrumentation recorders,
which were devices used to record N channels of analog data. Typically this was done by
FM-modulating that data for the actual recording process. I've seen references to
heads for such machines in widths from 1/4 inch to 2 inches depending on the number of
channels needed. I believe instrumentation tape was usually supplied on reels that look
like professional audio tape reels -- metal flanged reels with hubs somewhat larger than a
standard computer tape hub, with 3 small notches.
Some early computers used tape like that for data recording; for example, the
Electrologica X1 used 1/2 inch instrumentation tape reels, recording data at 400 DPI (NRZI
I think) in 10 (!) tracks. Those were vaguely like DECtape -- random access rewritable
blocks -- but with variable rather than fixed length blocks.
Recovering data from such reels is an interesting problem today.
paul