157 lines
4.0 KiB
Groff
157 lines
4.0 KiB
Groff
.\"
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.\" Copyright (c) 1996 Jonathan Stone.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Jonathan Stone.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $NetBSD: scc.4,v 1.8 2003/05/06 08:09:36 wiz Exp $
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.\"
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.Dd April 24, 2003
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.Dt SCC 4
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.Os
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.Sh NAME
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.Nm scc
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.Nd
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Zilog 8530 Serial Communications Controller interface
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.Sh SYNOPSIS
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.Cd "scc* at ioasic? offset ?"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for the
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.Tn Zilog
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8530 Serial Communications
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Controller
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.Pq Tn SCC
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via the
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.Tn IOASIC
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found on
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.Tn DECstation
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5000 models in the /100, /20, and /240 series
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.Po
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supported by
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.Nx Ns /pmax
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.Pc .
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.Pp
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Each
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.Tn SCC
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device has two serial ports.
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The
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.Tn DECstation
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5000 model 20 provides one
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.Tn SCC
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device.
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Other models provide two, but one port of each device is dedicated to
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mouse and keyboard input, respectively.
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.Pp
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Input and output for each line may set to one of following baud rates:
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50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
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19200, 38400, or 57600.
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.Pp
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Speeds up to 230400 are supported by the chip and the motherboard,
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but speeds higher than 57600 do not work reliably without an external
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clock signal.
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.Sh FILES
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.Bl -tag -width Pa -compact
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.It Pa /dev/ttya
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.It Pa /dev/ttyb
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.It Pa /dev/ttyc
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.It Pa /dev/ttyd
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.El
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.Pp
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The mapping from units to serial-hardware outlets is idiosyncratic.
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The even ports are wired serial connectors and the odd-numbered ports
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are reserved for mouse and keyboard.
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.Pp
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On machines with one port like
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.Tn "Personal DECstations" ,
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the single device is
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.Pa ttya .
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.Pp
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On the
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.Tn "5000/1xx"
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and
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.Tn "5000/2xx" ,
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the first serial port (default serial console) is
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.Pa ttyc
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and the second port is
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.Pa ttya .
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.Sh SEE ALSO
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.Xr intro 4 ,
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.Xr ioasic 4 ,
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.Xr ttys 5 ,
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.Xr MAKEDEV 8
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Bx 4.4 .
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.Pp
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The
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.Nm
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driver was also used for the
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.Tn IOASIC
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.Tn SCC
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found in
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.Tn DEC
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.Tn Alpha
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model 3000
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.Tn TurboCHANNEL
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based systems;
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.Nx Ns /alpha
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has since been converted to use the machine-independent
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.Xr zstty 4 .
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.Sh BUGS
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The
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.Tn IOASIC
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provides internal
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.Tn DMA
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channels that can be programmed to transfer up to 4096 bytes of
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data into, or out, of an
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.Tn SCC
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without
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further software intervention.
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This feature of the
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.Tn IOASIC
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is not yet supported.
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.Pp
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The mapping from device-special files (major and minor number) to chip
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and port is arguably backwards.
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.Tn ULTRIX
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tries to hide the hardware mapping, but
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.Nx
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does not.
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Users wanting to use
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.Tn ULTRIX
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compatible tty names
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.Pa /dev/tty0
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and
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.Pa /dev/tty1
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for the
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.Nm
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comm-port lines should make links or device-special files which match
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their hardware setup.
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