[HECnet] backwr?

Has anybody ever used this and had success with it?  The magic switches, please? backwr.c is a user contribution to klh10 to write tape files that can be 'mounted' on a 10/20.  It comes with no documentation nor does it describe its usage.  I puzzled out the command line parser and did: ./backwr -c -T -f ../k20mit-277/k20mit-277.tar > k20tar.tap I want to copy the tar file off the tape to try to read it on the 20 with the 20's implementation of tar. However, when I try to copy the file off the tape, I get ?File data error on file MTA0: If not backwr, what are alternative solutions?  The klh10 micro-engine's NI implementation has odd behavior in that if you do a download, you get megabit speeds.  If you try to upload on the other hand, you can barely crack 1 kilobaud.  So I'm currently uploading the tarball with Kermit, but at 1KBd, it's going to take three days.