1.\"	$OpenBSD: rtfps.4,v 1.8 2003/08/31 19:53:42 jmc Exp $
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3.\" Copyright (c) 1990, 1991 The Regents of the University of California.
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6.\" This code is derived from software contributed to Berkeley by
7.\" the Systems Programming Group of the University of Utah Computer
8.\" Science Department.
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33.\"     from: @(#)dca.4	5.2 (Berkeley) 3/27/91
34.\"	from: Id: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
35.\"
36.Dd August 7, 1994
37.Dt RTFPS 4
38.Os
39.Sh NAME
40.Nm rtfps
41.Nd multiplexing serial communications interface
42.Sh SYNOPSIS
43.Cd "rtfps0 at isa? port 0x1230 irq 10"
44.Cd "com* at rtfps? slave ?"
45or
46.Cd "pccom* at rtfps? slave ?"
47.Sh DESCRIPTION
48The
49.Nm
50driver provides support for IBM RT PC boards that multiplex together up to four
51.Rn EIA
52.Tn RS-232C
53.Pf ( Tn CCITT
54.Tn V.28 )
55or
56.Tn RS-422A
57communications interfaces.
58.Pp
59Each
60.Nm
61device is the master device for up to four
62.Nm com
63devices.
64The kernel configuration specifies these
65.Nm com
66devices as slave devices of the
67.Nm
68device, as shown in
69.Sx SYNOPSIS .
70The
71.Tn port
72specification for the
73.Nm
74device is used to compute the base addresses for the
75.Nm com
76subdevices.
77.Sh FILES
78.Bl -tag -width Pa
79.It Pa /dev/tty0?
80.El
81.Sh SEE ALSO
82.Xr com 4 ,
83.Xr intro 4 ,
84.Xr isa 4
85.Sh HISTORY
86The
87.Nm
88driver was written by Charles Hannum, based on the
89.Nm ast
90driver.
91.Sh BUGS
92The
93.Nm
94driver is unlikely to work on non-PCI machines.
95The ISA bus only asserts 10 I/O address lines, and this is not enough.
96.Pp
97Even on PCI machines, some address conflicts have been observed.
98On one machine, the second port always conflicted with something (though
99it's not clear what) and caused strange results.
100Disabling the second port in the kernel config allowed the other three
101ports to function correctly.
102