On 2/13/2016 6:33 AM, Christian Corti wrote: > On Thu, 11 Feb 2016, Christian Corti wrote: >> 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.
That makes sense: different formatters would be required. > > 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_Nov76.pdf 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
