share/man/man4/man4.i386/sio.4

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.\"     from: @(#)dca.4 5.2 (Berkeley) 3/27/91
.\"     from: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
.\"     $Id$
.\"
.Dd August 28, 1993
.Dt SIO 4 i386
.Os FreeBSD
.Sh NAME
.Nm sio
.Nd
fast interrupt serial communications interface
.Sh SYNOPSIS
.Cd "device sio0 at isa? port" \&"IO_COM1\&" tty irq 4 vector siointr
.Cd "device sio1 at isa? port" \&"IO_COM2\&" tty irq 3 vector siointr
.Cd "device sio2 at isa? port" \&"IO_COM3\&" tty irq 5 vector siointr
.Cd "device sio3 at isa? port" \&"IO_COM4\&" tty irq 9 vector siointr
.Sh DESCRIPTION
The
.Nm sio
driver provides support for NS8250-, NS16450-, and NS16550-based
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.28 )
communications interfaces.  The NS8250 and NS16450 have single character
buffers, and the NS16550 has a 16 character buffer.
.Pp
Input and output for each line may set to one of following baud rates;
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
19200, 38400, 57600, or 115200.
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/tty00
.It Pa /dev/tty01
.El
.Sh DIAGNOSTICS
.Bl -diag
.It sio%d: silo overflow.
The single-character input
.Dq silo
has overflowed and incoming data has been lost.
.\".It com%d: weird interrupt: %x.
.\"The device has generated an unexpected interrupt
.\"with the code listed.
.El
.Sh SEE ALSO
.Xr tty 4
.Xr com 4
.Sh HISTORY
The
.Nm
driver is derived from the
.Nm HP9000/300
.Nm dca
driver and is
.Ud
.Sh BUGS
Data loss is not near as likely on busy systems as they are with the
.Xr com 4
driver but they still can occur at very high baud rates on slow systems.
.Pp
The constants which define the locations
of the various seiral ports are holdovers from
.Nm DOS .
.Pp
As usual, you get what you pay for; cheap NS16550 clones
generally don't work.