opens and ioctls for 3B2 streaming cartridge tape

[Daniel R. Levy]

Can somebody who has worked with this or who has the documentation tell me how
the CTC cartridge tape for the 3B2 is supposed to be open()'ed and ioctl()'ed
and write()'ten to and read() from in order to get it to stream?   My depart-
ment has gotten a new 3B2/400, and it has a cartridge tape unit.  However, at-
tempts by mere mortal programs to read and write from /dev/rSA/ctape1 or
/dev/SA/ctape1 produce, not streaming, but a slow, bursty, noisy (and
undoubtedly very wearing) back-and-forth motion of the tape as the data
is transferred.  I know that true streaming is possible; ctccpio does it
(but has another flaw; it doesn't take to "at" or "batch" jobs because it
wants to open /dev/tty for writing--!).  Digging through the 
/usr/include/sys/ct*.h files gives allusions to ioctls (and a special open)
for the tape, but apparently nowhere in the voluminous documentation that came
with the 3B2 is this described.  (The cc, sgs, and esg utilities were installed
for us, and we do not have manuals for them yet--is it documented there?
termio(7) in the administrator's manual says nothing about how to control
this particular "character special device.")  It would be nice to have
general purpose "streamin" and "streamout" programs to stream reads and
writes, respectively, from and to the tape and to interface via stdout and
stdin, respectively, with other programs.  (Is this even possible?  This
would sound like an obvious pair of utilities to go with the tape.)

Thank you very much for any hints or information, or even telling me where to
look.  All replies will be personally acknowledged.

--Dan Levy--
AT&T Computer Systems Division, Skokie
..!ihnp4!ttrdc!levy