<div dir="auto"><div>It's always worth a shot to approach them. Although my hunch is the typical materials they use for audio drive belts is very different. The cartridge drive belts are very thin and with very little elasticity in comparison to an audio drive belt. And audio drive belts don't need to rapidly reverse direction and accelerate/decelerate. However if the classic computer community shows a wnough interest in replacement belts, it may be enough of a business case to get someone to get something made. I'm sure China has a fab that can made them to those original 3M specs. </div><div dir="auto"><br></div><div dir="auto">This has been something that has been on my mind for a while. It's a shame that all these cartridge tapes become completely inoperable due to a single band that could probably be made pretty easily with the right fab. I have some tapes that are still in shrink wrap that already have their bands snapped. I agree this whole use of plastibands and baking the old bands, etc is such a waste of time with such inconsistent results.</div><div dir="auto"><br></div><div dir="auto">Furthermore I think it's not just one time data extraction, but there is plenty of vintage hardware where the way to install the OS is through QIC tapes - I'm thinking early Sun and Apollo among others. So making aftermarket bands available would be in valuable from a preservation perspective to keep these machines running.</div><div dir="auto"><br></div><div dir="auto">-Kurt </div><div dir="auto"><br><br><div class="gmail_quote" dir="auto"><div dir="ltr" class="gmail_attr">On Fri, May 15, 2026, 08:08 John Hudak via rescue <<a href="mailto:rescue@sunhelp.org" target="_blank" rel="noreferrer">rescue@sunhelp.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>I've seen/read a number of 'gum band/rubber band approaches to find replacement belts for the tape transports. Why not get a 'real' belt from houses that sell replacement belts for classic audio gear? It is fairly easy to measure for the length of a belt, and the width which can be used to find a replacement.
There are guides on the web that explain how to take into account
tightness/stretch to have it function properly and avoid over tightening
that will cause bearing degradation and misalignment.
Many places have interactive search windows in which you enter the belt specifics and it will search its data base for the closest match.</div><div>Some places will actually make a belt to your specs. Places I've dealt with in the past include:</div><div>Turntableneedles.com, <a href="http://lpgear.com" rel="noreferrer noreferrer" target="_blank">lpgear.com</a>, <a href="http://vintage-electronics.net" rel="noreferrer noreferrer" target="_blank">vintage-electronics.net</a>, <a href="http://turntabledrivebelts.com" rel="noreferrer noreferrer" target="_blank">turntabledrivebelts.com</a>.</div><div>One can also get a belt that is close that can be cut and glued to the appropriate length. This approach works best for flat belts although it can be done with square or rectangular belts with some patience and good dexterity.</div><div>Am surprised this hasn't been done before given the number of digital tape machines out there. </div><div><br></div><div>I get the idea of a quick fix just to get data off of tapes and never use the device again but all that time to try various suppliers products without repeatability seems like a huge time sink. In addition, the findings may not be repeatable. The designated mfg may change the product. Eventhough they may claim the same, it can be different</div><div>J</div><div>.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, May 15, 2026 at 9:36\u202fAM Alan Perry via rescue <<a href="mailto:rescue@sunhelp.org" rel="noreferrer noreferrer" target="_blank">rescue@sunhelp.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<p>I have the green plastibands and the clear bands. I have found
that the clear bands have too much tension and can lift material
from the tape. The tension of the green bands vary and it seems
like there is a window where they work best.</p>
<p>The tapes came with a Sun 3/160 based Model 32, and some are
clearly for it. My goal is to restore the CADDStation and I hope
all of the software is there on the tapes.</p>
<p>Where can one find copytape for SunOS?</p>
<p>I was able to use tapetool to extract a file called tapedir from
two different tapes</p>
<p>alan</p>
<div>On 5/14/26 11:35 AM, Clem Cole wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">First, what are
you using for bands? (size and manufacturer).</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">With regard to
the tape itself, given that these are old tapes, assume you
will get one shot in the transport. So I
>>highly<< recommend using the old 1985 copytape
utility <span style="border-style:none;background:none">from the</span>
USENET (pdf of its man <span style="border-style:none;background:none">page of</span> the
command and the format it <span style="border-style:none;background:none">writes</span>
attached), and creating a tape image you can decode without
needing to touch either the tape or the transport. If you
don't have it, send me an email off-list, and I'll be happy to
provide it to you.</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="border-style:none;background:none">copytape</span>
will attempt to read 262144 (256K) bytes at a time. On a QIC
drive, which has fixed-size (512-byte) records, that <span style="border-style:none;background:none">will
equate</span> to 512 <span style="border-style:none;background:none">blocks (on</span>
a 9-<span style="border-style:none;background:none">track,</span>
which used variable-sized records, each 256k read, will return
as many bytes as were written on that tape record, which can<span style="border-style:none;background:none">
be a small integer to no more than 65536</span> (64K
bytes). Copytape will read tape marks. Tape "files" are
delineated by tape marks. On drivers that were written
properly, the last "tape file" will have a second tape mark [<i>i.e.</i>,
two in a row] to delineate EOT. Note that many of the QIC
drivers do not do that (and neither did Ken's original 9-track
tape driver for Fifth Edition and IIRC Sixth, but by then a
number of us had rewritten to 9-track drivers <span style="border-style:none;background:none">to
be </span> much smarter, but I digress)<br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Once you have a
copy of the tape in "copytape" format, you can decode it much
more easily.</div>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br>
</div>
<div class="gmail_default"><span style="font-family:arial,helvetica,sans-serif">A</span><font face="arial, sans-serif">s for the format itself, it
depends on which Computer Vision system wrote it. Their
early systems were based on DG Novas and ran RDOS (similar
to DEC's RT11). From the late 70s until the mid 1980s, they
replaced RDOS with their own OS called CGOS (<span style="color:rgb(10,10,10)">Computervision Graphics
Operating System), and by the late 80's, early 90's, they
had ported their CADDS system to run on UNIX and started
shipping it on Suns. Finally, <span style="border-style:none;background:none">they got
bought by Prime, and then</span> moved it again to
PRIMOS.</span></font></div>
<div class="gmail_default"><font face="arial, sans-serif"><span style="color:rgb(10,10,10)"><br>
</span></font></div>
<div class="gmail_default"><font face="arial, sans-serif"><span style="color:rgb(10,10,10)">Given
that this is a QIC tape, the time frame says either late
CGOS or SunOS, although Prime might have supported QIC; I
never saw anything but 9-track on their systems.</span></font></div>
<div class="gmail_default"><font face="arial, sans-serif"><span style="color:rgb(10,10,10)"><br>
</span></font></div>
<div class="gmail_default"><font face="arial, sans-serif"><span style="color:rgb(10,10,10)">So
... if it was written on an early CV system, it is likely
to be in what DG called MTIO format or possibly in the DG
backup format. </span></font>Data General\u2019s RDOS natively
used raw, streaming sequential blocks without a complex,
metadata-heavy file system structure, such as ANSI labeled
tapes (DEC often used a superset - embrace and extend - ANSI
tape format). I don't know what CGOS used, but I suspect it
was similar to the DG style. If it was written on a Sun or
other UNIX box, it is likely to be TAR (hopefully) or CPIO.
If the latter, there is a slew of different CPIO on tape
formats - this is historical because<span style="border-style:none;background:none"> it</span> was
created for PDP-11s and was a binary format.<font face="arial, sans-serif"><span style="color:rgb(10,10,10)">
It could also be one of the many UNIX backup formats, so
you will need to do a little examination to determine
which one. Modern versions of the original V7 Unix
file(1) >>might<< be able to identify the
format. Finally, l</span></font><span style="font-family:arial,sans-serif;color:rgb(10,10,10)">ike
DG, Prime opted not to use DEC-style (pseudo-ANSI) labeled
file structures natively. Instead, they also created their
own proprietary, streaming binary format deeply tied to
PRIMOS\u2019s unique disk architecture and </span>character
encodings. I've never seen documentation on this format.</div>
<div class="gmail_default"><font face="arial, sans-serif"><span style="color:rgb(10,10,10)"> </span></font></div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, May 14, 2026 at
9:44\u202fAM Alan Perry via rescue <<a href="mailto:rescue@sunhelp.org" rel="noreferrer noreferrer" target="_blank">rescue@sunhelp.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I
seem to have found a working combination of drive and
replacement's bands to be able to get images of the dozens of
Computervision install tapes that I have.<br>
<br>
They are QIC-24 from the late 80s and aren\u2019t in the
\u201ccollection of tar files\u201d format that I usually use mt fsf and
dd to read. Each tape starts with a file with a \u201ctapedir\u201d
record with permission and other stuff, followed by a bunch of
records that look like a number followed by a topic or title.
What am I looking at and what do I use to get the info off of
the tape?<br>
<br>
alan<br>
<br>
<br>
<br>
<br>
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</blockquote>
</div>
</blockquote>
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