dn.4

早期freebsd实现

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.\"     @(#)dn.4	8.1 (Berkeley) 6/5/93
.\"
.Dd June 5, 1993
.Dt DN 4 vax
.Os BSD 4
.Sh NAME
.Nm dn
.Nd
.Tn DN-11
autocall unit interface
.Sh SYNOPSIS
.Cd "device dn0 at uba? csr 0160020 vector dnintr"
.Sh DESCRIPTION
The
.Nm dn
device provides an interface through a
.Tn DEC
.Tn DN-11
(or equivalent
such as the Able Quadracall) to an auto-call unit
.Pq Tn ACU .
To place an outgoing call one forks a sub-process which
opens the appropriate call unit file,
.Pa /dev/cua?
and writes the phone number on it.  The parent process
then opens the corresponding modem line
.Pa /dev/cul? .
When the connection has been
established, the open on the modem line
.Pa /dev/cul?
will return and the process will be connected.
A timer is normally used to timeout the opening of 
the modem line.
.Pp
The codes for the phone numbers are:
.Bl -column xxxx -offset indent
0-9	number to be dialed
*	dial * (`:' is a synonym)
#	dial # (`;' is a synonym)
\-	delay 20 milliseconds
<	end of phone number (`e' is a synonym)
=	delay for a second dial tone (`w' is a synonym)
f	force a hangup of any existing connection
.El
.Pp
The phone number to be dialed must be presented as one contiguous string.
.Pp
By convention, even numbered call units are for 300 baud
modem lines, while odd numbered units are for 1200 baud lines.
For example,
.Pa /dev/cua0
is associated with a 300 baud modem line,
.Pa /dev/cul0 ,
while
.Pa /dev/cua1
is associated with a 1200 baud modem line,
.Pa /dev/cul1 .
For devices such as the Quadracall which simulate multiple
.Tn DN-11
units, the minor device indicates which outgoing modem to use.
.Sh FILES
.Bl -tag -width /dev/cul? -compact
.It Pa /dev/cua?
call units
.It Pa /dev/cul?
associated modem lines
.El
.Sh DIAGNOSTICS
Two error numbers are of interest at open time.
.Bl -tag -width EBUSYxx
.It Bq Er EBUSY
The dialer is in use.
.It Bq Er ENXIO
The device doesn't exist, or there's no power to it.
.El
.Sh SEE ALSO
.Xr tip 1
.Sh HISTORY
A
.Nm
driver appeared in
.At v6 .