[rescue] Getting QIC tapes images

[Clem Cole]

First, what are you using for bands?  (size and manufacturer).

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 from the USENET (pdf of its man page of the
command and the format it writes 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.

copytape will attempt to read 262144 (256K) bytes at a time.  On a QIC
drive, which has fixed-size (512-byte) records, that will equate to 512 blocks
(on a 9-track, which used variable-sized records, each 256k read, will
return as many bytes as were written on that tape record, which can be a
small integer to no more than 65536 (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.e.*,
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 to
be  much smarter, but I digress)

Once you have a copy of the tape in "copytape" format, you can decode it
much more easily.

As 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 (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, they got bought by Prime,
and then moved it again to PRIMOS.

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.

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.  Data General’s
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 it was created for PDP-11s and was a binary
format.   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, like 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’s unique disk architecture
and character encodings.  I've never seen documentation on this format.


On Thu, May 14, 2026 at 9:44 AM Alan Perry via rescue <rescue at sunhelp.org>
wrote:

> 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.
>
> They are QIC-24 from the late 80s and aren’t in the “collection of tar
> files” format that I usually use mt fsf and dd to read. Each tape starts
> with a file with a “tapedir” 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?
>
> alan
>
>
>
>
> _______________________________________________
> rescue list - http://sunhelp.org/mailman/listinfo/rescue_sunhelp.org
>
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