[TUHS] Choice of Tape Format for BTL UNIX Distro

[Arnold Robbins via TUHS]

In that time frame, 800 BPI was pretty standard. 9 tracks gave you
eight bits of data plus a parity bit.

By the mid-80s, 1600 BPI was pretty common for the same media, so
the BSD distributions might have been 1600 BPI tapes.

I think at some point 9 track tape drives hit something like 6400 BPI,
but I may be hallucinating the memory.

HTH,

Arnold

segaloco via TUHS <tuhs at tuhs.org> wrote:

> Surprise surprise, another hyper-specific topic incoming.  I am curious
> if anyone on-list can provide insight on this topic.  Setting Up Unix -
> Seventh Edition indicates:
>
> > The tape is 9-track 800 BPI...
>
> Was this a matter of convention given the general computing ecosystem at
> the time, or was this more driven by Bell System standards for magtape?
>
> I find myself curious as I recently procured a 7-track 556 BPI transport
> which, while not applicable to V7 UNIX tapes as so described, has me
> itching to explore the world of magtape further, including eventually
> tracking down a 9-track supporting the necessary BPI should another UNIX
> tape needing preservation surface.
>
> I also recently got a QIC drive (not the right size for the early 90s
> BTL tapes I have) and am exploring repurposing the read head to yank
> data off these janky QIC tapes I have.  Needless to say, magnetic tape
> media and preservation is on the mind lately.
>
> Further on the subject of UNIX tapes though, was there any regular
> shipment of other media not matching this description or was it pretty
> settled that
>
> order_unix()
>
> has a return type of
>
> mt_track_9_bpi_800_t
>
> ?
>
> - Matt G.