14 Feb
2016
14 Feb
'16
2:08 p.m.
On 2/13/2016 6:33 AM, Christian Corti wrote:
On Thu, 11 Feb 2016, Christian Corti wrote:
That makes sense: different formatters would be required.
I have a 7970B (-236) with options 127, 006, 007,
012 and 023.
According to the HP 1000 Peripherals Selection Guide from 1982, page 16,
option 236 specifies an 800bpi master magnetic tape subsystem with one
drive and two-card 13181B interface.
And you can't mix 800 and 1600 bpi on the same interface for the HP
1000. You need either the 13181 for NRZI, or the 13183 for PE.
So, apparently my NRZI 9 track drive has the density option included,
and I don't know if there were any other 200/556 bpi 9 track drives out
there. When we got the drive I had hoped it would be a 7 track drive,
but it isn't.
Christian
I have never heard of 200bpi or 556bpi for anything other than 7 track.
I cannot imagine why anyone would ever produce such a thing. The only
density I have ever heard of as being available on both 7 track and 9
track is 800BPI NRZI, from any manufacturer, and I have seen quite a lot
of them over the years. Nor have I ever seen a 9 track tape whose label
on the exterior claimed it had been written at 200 BPI or 556 BPI.
Your S/N has prefix 1124, so it looks like this manual is applicable:
http://bitsavers.trailing-edge.com/pdf/hp/tape/7970/07970-90886_7970drws_No…
Looking at this manual for the 7970B / 7970E I see that dual 7/9 track
heads did exist. Yours has a plate that claims it has option 127 (as
well as 6, 7, 12 and 23). The 127 implies a 9 track only head, but I
suggest you pull the head cover off to see if you can find a part
number. What the plate claims, and what the machine actually is can
differ for all sorts of reasons. And the sticker is coming off at the
edges as well - it may have been *moved* from one frame to another.
Wouldn't be the first time - particularly in a university setting.
The buttons clearly imply a NRZI drive (rather than 1600 BPI PE).
JRJ