Name

dn − DN-11 autocall unit interface

Syntax

device dn0 at uba? csr 0160020 vector dnintr

Description

The dn device provides an interface through a DEC DN-11 (or equivalent such as the Able Quadracall) to an auto-call unit (ACU).  To place an outgoing call one forks a sub-process which opens the appropriate call unit file, /dev/cua?  and writes the phone number on it.  The parent process then opens the corresponding modem line /dev/cul?. When the connection has been established, the open on the modem line, /dev/cul?  will return and the process will be connected.  A timer is normally used to timeout the opening of the modem line. 

The codes for the phone numbers are:

0-9dial 0-9
*dial * (‘:’ is a synonym)
#dial # (‘;’ is a synonym)
−delay 20 milliseconds
<end-of-number (‘e’ is a synonym)
=delay for a second dial tone (‘w’ is a synonym)
fforce a hangup of any existing connection

The entire telephone number must be presented in a single write system call. 

By convention, even numbered call units are for 300 baud modem lines, while odd numbered units are for 1200 baud lines.  For example, /dev/cua0 is associated with a 300 baud modem line, /dev/cul0, while /dev/cua1 is associated with a 1200 baud modem line, /dev/cul1. For devices such as the Quadracall which simulate multiple DN-11 units, the minor device indicates which outgoing modem to use.

Files

/dev/cua?call units
/dev/cul?associated modem lines

See Also

tip(1C)

Diagnostics

Two error numbers are of interest at open time. 

[EBUSY] The dialer is in use. 

[ENXIO] The device doesn’t exist, or there’s no power to it.