[Simh] Mag tape interface

[Jon Elson]

Well, I am now really close to having a mag tape drive working on
a Linux system.  The docs confused me, so the bit ordering is
backwards.  That will be easy to fix.  It is not detecting file marks,
they just show up as zero-length records.  I'll have to track that
down.

What I will do next is write a program that reads in a whole
tape to a disk file that is an exact representation of the tape.
So, there would be a 32-bit record indicator that would be 1-65536
for a block of data, -1 for a file mark, and -2, etc. for various
errors.

Then, I can write programs that will extract the individual files from 
this file
for simple formats.

Jon