Hello Bryan,

to access tape or DDS devices with tar, you need to setup
a device link (device file) using mknod.hpbin.sys first...

:MKNOD.HPBIN.SYS "/dev/mytape c 0 7"

or, if you prefer the shell

$ mknod /dev/mytape c 0 7

The "c" is for "character device" (as opposed to "b" for
"block device"), the 0 is major number and the 7 (in my
example) is the LDEV number.

In case my memory fooled me, you should be able to check
the details in either the Update or PowerPatch manuals or
using the man page inside the shell.

Regards, Lars/iX

PS: Unlike UX you will still get a reply request on the
    console (unless your device is configured autoreply).