On Aug 7, 2019, at 10:06 PM, Paul Anderson <useddec at gmail.com> wrote: I think you could change heads in a TU10 and add or take out a few boards. I've worked on 7 and 9 track versions in the day. > On Wed, Aug 7, 2019 at 6:43 PM Michael Thompson via cctech <cctech at classiccmp.org> wrote: > > > > thanks a lot for your hint to the DEC controller. I wasn't aware that the > > TM11, TMA11 and TMB11 controllers can handle 9-track as well as 7-track > > NRZI-encoded tape drives. However, all these controllers seem to be very > > rare in the public out there. Not too surprising considering that DEC TU > > and TS tape drives themselves are rare and that 7-track tape drives were > > soon replaced by 9-track tape technology in the early days. > > > > With best regards, > > Pierre > > > > The TC58 Magnetic Tape Controller for the PDP-8 and the TC59 for the PDP-9 > can be connected to both 7-track and 9-track drives. The TU20 drive on the > PDP-9 at the RICM is a 7-track drive. The only difference between the > 7-track and 9-track versions of the TU20 is the tape head. All of the tape > drive electronics is the same for both versions. > > -- > Michael Thompson

On Wed, 7 Aug 2019, Michael Thompson wrote: The same is true for the HP 7970B tape drives, I even have a 9-track 7970B that can be switched between 200, 556 and 800 bpi. I only need a 7-track head...