| DN(4) | Kernel Interfaces Manual (VAX) | DN(4) |
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 | 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 |
The phone number to be dialed must be presented as one contiguous string.
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.
| June 5, 1993 | NetBSD 6.1 |