Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!rjn
From: rjn@hpfcdc.HP.COM (Bob Niland)
Newsgroups: comp.sys.hp
Subject: Re: tcio(1)
Message-ID: <5570172@hpfcdc.HP.COM>
Date: 8 May 89 23:04:25 GMT
References: <2105@litp.UUCP>
Organization: HP Ft. Collins, Co.
Lines: 29

re: "I have used the "tcio(1)" command to drive an HP9144 from a 9000/319..."

> - from the documentation, I understand that "-S <n>" specifies
>   the size of memory allocated by "tcio" for its use and is without
>   relation with the physical encoding on the tape.

It implicitly specifies the maximum I/O request sent across HP-IB.  Keeping
it below the buffer size in the tape drive (12K or so) prevents the bus from
being temporarily hung up waiting for data to make it to the tape media.

>   ...                                              However, I have
>   noticed tapes written with -S 8 that could not be read again
>   without this option.

The use of "S" with any value should have no effect on the data written to
the tape.

> - I have a similar problem with the "-Z" option. From the documentation
>   I understand that this option allows a binary copy. 

Not exactly.  The default operation of tcio is to write an EOF (zero-length
block as I recall) at the beginning of the tape and at /dev/rct close.
This prevents accidental push-button copying of the tape to a 7908, 791x or
7942/46 disk drive.  If you write with "Z" but don't specify it upon read,
tcio will probably skip the first 1K [data] block, presuming that it is a ZLR.

Regards,                                              Hewlett-Packard
Bob Niland        rjn%hpfcrjn@hplabs.HP.COM           3404 East Harmony Road
                  [hplabs|hpu...!hpfcse]!rjn          Ft Collins CO 80525-9599