.\"	$OpenBSD: mt.4,v 1.7 2003/03/06 17:59:21 jason Exp $
.\"	$NetBSD: mt.4,v 1.3 1996/03/03 17:13:52 thorpej Exp $
.\"
.\" Copyright (c) 1980, 1991 Regents of the University of California.
.\" All rights reserved.
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.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
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.\"     from: @(#)mt.4	6.4 (Berkeley) 3/27/91
.\"
.Dd March 27, 1991
.Dt MT 4 vax
.Os
.Sh NAME
.Nm mt
.Nd
.Tn TM78 Ns / Tn TU-78
.Tn MASSBUS
magtape interface
.Sh SYNOPSIS
.Cd "mt* at mscpbus? drive?"
.Sh DESCRIPTION
The
.Tn TM78 Ns / Tn TU-78
combination provides a standard tape drive
interface as described in
.Xr mtio 4 .
Only 1600 and 6250
.Tn BPI
are supported; the
.Tn TU-78
runs at 125
.Tn IPS
and autoloads tapes.
.Sh DIAGNOSTICS
.Bl -diag
.It mu%d: no write ring.
An attempt was made to write on the tape drive
when no write ring was present; this message is written on the terminal of
the user who tried to access the tape.
.Pp
.It mu%d: not online.
An attempt was made to access the tape while it
was offline; this message is written on the terminal of the user
who tried to access the tape.
.Pp
.It "mu%d: can't change density in mid-tape."
An attempt was made to write
on a tape at a different density than is already recorded on the tape.
This message is written on the terminal of the user who tried to switch
the density.
.Pp
.It "mu%d: hard error bn%d mbsr=%b er=%x ds=%b."
A tape error occurred
at block
.Em bn ;
the mt error register and drive status register are
printed in octal with the bits symbolically decoded.
Any error is fatal on non-raw tape; when possible the driver will have retried
the operation which failed several times before reporting the error.
.Pp
.It mu%d: blank tape.
An attempt was made to read a blank tape (a tape without even
end-of-file marks).
.Pp
.It mu%d: offline.
During an i/o operation the device was set offline.
If a non-raw tape was used in the access it is closed.
.El
.Sh SEE ALSO
.Xr mt 1 ,
.Xr intro 4 ,
.Xr mscpbus 4
.Sh HISTORY
The
.Nm
driver appeared in
.Bx 4.1 .
.Sh BUGS
If a physical error (non-data) occurs,
.Nm
may hang ungracefully.
.Pp
Because 800
.Tn BPI
tapes are not supported, the numbering of minor devices
is inconsistent with triple-density tape units.
Unit 0 is drive 0, 1600
.Tn BPI.