I found a reference to vtserver on Johnathan Engdahl's web site here . It was written by Warren Toomey and can be found on his web site . It seemed to solve a problem I had (if it worked) of how to get system images onto a PDP-11 so that they could be used.
Fundamentally vtserver is a program that runs on a Unix or Linux host that emulates a simple terminal and a virtual tape drive. Also included in the package are standalone programs that can be downloaded to the PDP-11 (using vtserver of course) that allow copying of the data from the virtual tape device (the host) and writing it to a device on the PDP-11. Since vtserver was derived from the standalone programs for BSD, it has pretty much full generality, so one could use it to perform standalone copies of packs between drives. I guess it could also be used to copy from a real tape device to a disk too.
It's fairly simple to set up (just follow the directions in
the
readme
). I had it up and running on my Linux laptop in about 5 minutes
(including
the time it took to type 'make').