Path: utzoo!attcan!uunet!husc6!cfa!ward
From: ward@cfa.harvard.EDU (Steve Ward)
Newsgroups: comp.periphs
Subject: Re: Streaming Tapes with Floppy Intefaces
Summary: QIC-40 floppy I/O tape drives
Message-ID: <1025@cfa.cfa.harvard.EDU>
Date: 17 May 88 18:42:32 GMT
References: <2922@emory.uucp>
Organization: Harvard-Smithsonian Ctr. for Astrophysics
Lines: 61

In article <2922@emory.uucp>, km@emory.uucp (Ken Mandelberg) writes:
> There are several companies which make 40 Meg streaming tape drives
> with a form factor and interface compatible with a 5.25 inch floppy
> disk. They are meant for an IBM PC and are meant to use the existing
> floppy controller.  A device driver for the PC is provided.
> 
> What I'm really wondering is how to use one of these to replace a
> floppy on a Unix machine (the 3B1 particularly).  I'm wondering if its
> possible to just plug in the tape instead of the floppy and use a
> sequence of read/write/lseek on the "floppy" device file to manipulate
> the tape.


You cannot just swap the tape drive in place of the floppy drive.

There are several versions of floppy I/O tape drives, and maybe someone
makes one that truly emulates a floppy disk drive, but I am unaware of
any.  typically the minimum data block size (sector) is much larger than
512 bytes and the number of floppy "tracks" and "sectors/track" varies
considerably from a real floppy disk drive.  This means that at a
minimum you need a unique device driver or tape utility program to use
these tape drives.

Some of them conform to the QIC-40 specification.  These will allow
exchange of data cartridges (assuming complete compliance to QIC-40)
among different vendor QIC-40 tape drives.  This multi-vendor 
interchange capability does not exist among non-QIC-40 tape drives,
even though they may use the same DC2000 (or whatever) digital tape
cartridge.  For this reason you are better off using the QIC-40
tape drive.  Still, you are faced with writing a device driver and/or
a tape drive utility program.  The drives offered for the PC come
with the necessary software.  For use with non-PC computers you
will have to write your own.

If you are interested in interfacing and using QIC-40 tape drives
for backup on small workstation computers (PC's, Unix boxes, MicroVAXen,
etc) then please send me your name, e-mail and postal mail addresses
and phone number.  A second use of these tape drives is as a data
interchange medium.  The QIC-40 standard assures exchange because it
also defines the data storage (incl. hierarchical file naming)
format.  I am looking into this and would be willing to send out
updates to an informal mail list.  Indicate whether you might be
willing to help write software.  I might be able to supply hardware
for development/test purposes to a couple of people.  BTW, these
QIC-40 drives are available with floppy disk I/O as noted, and
also with SCSI I/O as well.  There is a big gap in cost, convenience,
and storage capacity for data interchange among computers between
the lowly floppy and nine-track tape, the only two near-universal
exchange media.  QIC-40 may prove to be a near-floppy cost, 40MB
capacity near-universal data interchange medium.

Steven M. Ward
Harvard-Smithsonian Observatory
60 Garden Street, M/S 25
Cambridge, MA 02138
(617)495-7201

ward@cfa.harvard.edu
{ihnp4,seismo}!harvard!cfa!ward

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