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@(#)dn.4 6.1 (Berkeley) 05/15/85

C 4 dn - DN-11 autocall unit interface "device dn0 at uba? csr 0160020 vector dnintr" 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:

0-9 dial 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)
f force 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.

/dev/cua? call units

/dev/cul? associated modem lines

tip(1C) Two error numbers are of interest at open time.

10 [EBUSY] The dialer is in use.

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