+.\" Copyright (c) 1986, 1991 The Regents of the University of California.
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" 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
+.\" without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" @(#)mtio.4 6.4 (Berkeley) 5/6/91
+.\"
+.Dd May 6, 1991
+.Dt MTIO 4
+.Os
+.Sh NAME
+.Nm mtio
+.Nd
+.Tn UNIX
+magtape interface
+.Sh DESCRIPTION
+The special files named
+.Pa /dev/cy0s ,
+...,
+.Pa /dev/cy15s
+are interfaces to the
+.Tn UNIX
+magtape drivers.
+For the
+Tahoe, these interfaces
+may be on the
+.Tn VERSABUS
+via a
+.Tn CIPHER
+tapemaster formatter
+.Xr cy 4 .
+The files
+.Pa cy0s ,
+...,
+.Pa cy15s
+are read/written in 25
+.Tn IPS ,
+The density (1600
+.Tn BPI
+or 3200
+.Tn BPI )
+is selected by a switch on the drive.
+The following table of device names
+applies to any of the transport/controller pairs.
+.Bl -column "rewindxxx" "No-rewindxxx" "rewindxxxx" "No-rewindxxxx" -offset indent
+.Em Rewind No-rewind Rewind No-rewind
+cy0s/rcy0s ncy0s/nrcy0s cy8s/rcy8s ncy8s/nrcy8s
+cy1s/rcy1s ncy1s/nrcy1s cy9s/rcy9s ncy9s/nrcy9s
+cy2s/rcy2s ncy2s/nrcy2s cy10s/rcy10s ncy10s/nrcy10s
+cy3s/rcy3s ncy3s/nrcy3s cy11s/rcy11s ncy11s/nrcy11s
+cy4s/rcy4s ncy4s/nrcy4s cy12s/rcy12s ncy12s/nrcy12s
+cy5s/rcy5s ncy5s/nrcy5s cy13s/rcy13s ncy13s/nrcy13s
+cy6s/rcy6s ncy6s/nrcy6s cy14s/rcy14s ncy14s/nrcy14s
+cy7s/rcy7s ncy7s/nrcy7s cy15s/rcy15s ncy15s/nrcy15s
+.El
+.Pp
+The rewind devices automatically rewind
+when the last requested read, write or seek has finished, or the end of the tape
+has been reached. The letter
+.Ql n
+is usually prepended to
+the name of the no-rewind devices.
+.Pp
+For compatibility with customary
+.Tn UNIX
+tape device
+names
+.Dq Em mt* ,
+the
+.Bo Pa n Bc Pa cy*s
+files are linked to appropriate
+.Bo Pa n Bc Em mt*
+files.
+.Pp
+Unix tapes are written in multiples of 1024 byte block
+records. Two end-of-file markers mark the end of a tape, and
+one end-of-file marker marks the end of a tape file.
+If the tape is not to be rewound it is positioned with the
+head in between the two tape marks, where the next write
+will over write the second end-of-file marker.
+.Pp
+All of the magtape devices may be manipulated with the
+.Xr mt 1
+command.
+.Pp
+A number of other
+.Xr ioctl 2
+operations are available
+on raw magnetic tape.
+The following definitions are from
+.Aq Pa sys/mtio.h :
+.Bd -literal
+/*
+ * Structures and definitions for mag tape io control commands
+ */
+
+/* structure for MTIOCTOP - mag tape op command */
+struct mtop {
+ short mt_op; /* operations defined below */
+ daddr_t mt_count; /* how many of them */
+};
+
+/* operations */
+#define MTWEOF 0 /* write an end-of-file record */
+#define MTFSF 1 /* forward space file */
+#define MTBSF 2 /* backward space file */
+#define MTFSR 3 /* forward space record */
+#define MTBSR 4 /* backward space record */
+#define MTREW 5 /* rewind */
+#define MTOFFL 6 /* rewind and put the drive offline */
+#define MTNOP 7 /* no operation, sets status only */
+#define MTCACHE 8 /* enable controller cache */
+#define MTNOCACHE 9 /* disable controller cache */
+
+/* structure for MTIOCGET - mag tape get status command */
+
+struct mtget {
+ short mt_type; /* type of magtape device */
+/* the following two registers are grossly device dependent */
+ short mt_dsreg; /* ``drive status'' register */
+ short mt_erreg; /* ``error'' register */
+/* end device-dependent registers */
+ short mt_resid; /* residual count */
+/* the following two are not yet implemented */
+ daddr_t mt_fileno; /* file number of current position */
+ daddr_t mt_blkno; /* block number of current position */
+/* end not yet implemented */
+};
+
+/*
+ * Constants for mt_type byte. These are the same
+ * for controllers compatible with the types listed.
+ */
+#define MT_ISTS 0x01 /* TS-11 */
+#define MT_ISHT 0x02 /* TM03 Massbus: TE16, TU45, TU77 */
+#define MT_ISTM 0x03 /* TM11/TE10 Unibus */
+#define MT_ISMT 0x04 /* TM78/TU78 Massbus */
+#define MT_ISUT 0x05 /* SI TU-45 emulation on Unibus */
+#define MT_ISCPC 0x06 /* SUN */
+#define MT_ISAR 0x07 /* SUN */
+#define MT_ISTMSCP 0x08 /* DEC TMSCP protocol (TU81, TK50) */
+#define MT_ISCY 0x09 /* CCI Cipher */
+#define MT_ISCT 0x0a /* HP 1/4 tape */
+#define MT_ISFHP 0x0b /* HP 7980 1/2 tape */
+#define MT_ISEXABYTE 0x0c /* Exabyte */
+#define MT_ISEXA8200 0x0c /* Exabyte EXB-8200 */
+#define MT_ISEXA8500 0x0d /* Exabyte EXB-8500 */
+#define MT_ISVIPER1 0x0e /* Archive Viper-150 */
+#define MT_ISPYTHON 0x0f /* Archive Python (DAT) */
+#define MT_ISHPDAT 0x10 /* HP 35450A DAT drive */
+
+/* mag tape io control commands */
+#define MTIOCTOP _IOW('m', 1, struct mtop) /* do a mag tape op */
+#define MTIOCGET _IOR('m', 2, struct mtget) /* get tape status */
+#define MTIOCIEOT _IO('m', 3) /* ignore EOT error */
+#define MTIOCEEOT _IO('m', 4) /* enable EOT error */
+
+#ifndef KERNEL
+#define DEFTAPE "/dev/rmt12"
+#endif
+
+#ifdef KERNEL
+/*
+ * minor device number
+ */
+
+#define T_UNIT 003 /* unit selection */
+#define T_NOREWIND 004 /* no rewind on close */
+#define T_DENSEL 030 /* density select */
+#define T_800BPI 000 /* select 800 bpi */
+#define T_1600BPI 010 /* select 1600 bpi */
+#define T_6250BPI 020 /* select 6250 bpi */
+#define T_BADBPI 030 /* undefined selection */
+#endif
+.Ed
+.Sh FILES
+.Bl -tag -width /dev/nrcy? -compact
+.It Pa /dev/cy? ,
+.It Pa /dev/rcy?
+Rewind devices.
+.It Pa /dev/ncy? ,
+.It Pa /dev/nrcy?
+No-rewind devices.
+.It Pa /dev/[n]mt? ,
+.It Pa /dev/[n]rmt?
+Linked device names.
+.El
+.Sh SEE ALSO
+.Xr mt 1 ,
+.Xr tar 1 ,
+.Xr cy 4
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