Talking Serially: Modem Configuration in IRIX

Dial-In Configuration

First, disable the serial port so that the modem may be configured. Edit the /etc/inittab to turn off the port to be used. The third field of the entry should contain the word off. For example:

t2:23:off:/sbin/getty -N ttyd2 co_9600          # port 2

Be sure to activate the new inittab with telinit q.

IRIX provides various modem configuration scripts in /etc/uucp for different vendor's modems (fix-dsi, fix-hayes, fix-intel, fix-telebit, fix-usr, fix-zyxel). Pick the one that best suits your modem If a script for the modem's vendor does not exist, and the modem is Hayes-compatible, try using the fix-hayes script. Run the script specifying a dial-in modem (-i), the port speed (-s speed), and the port number. For example:

/etc/uucp/fix-usr -i -s 38400 2

Now edit the /etc/inittab again to enable the modem port to be used and spawn a getty process to set the port configuration and allow logins. The current entry in the inittab will look something like this:

t2:23:off:/sbin/getty -N ttyd2 co_9600          # port 2

Change it to look something like the following:

t2:23:respawn:/sbin/getty -N ttyf2 dx_38400       # port 2

The things to concentrate on:

Change off to respawn.
Change ttyd2 to one of ttym2 or ttyf2. ttym* is for use with low-speed modems. ttyf* is for use with high-speed modems as it enables hardware flow control on the port. With most modern modems, ttyf* will be the one needed.
Change co_9600 to dx_speed where speed is the configured port speed.

Activate the new inittab with telinit q, and the modem should be ready for dial-in use.

Dial-Out Configuration

First, disable the serial port so that the modem may be configured. Edit the /etc/inittab to turn off the port to be used. The third field of the entry should contain the word off. For example:

t2:23:off:/sbin/getty -N ttyd2 co_9600          # port 2

Be sure to activate the new inittab with telinit q.

Configure the modem using the appropriate modem configuration script, this time specifying a dial-out modem (-o), the port speed (-s speed), and the port number. For example:

/etc/uucp/fix-usr -o -s 38400 2

Now edit the /etc/uucp/Devices file to create an entry for the modem port. Include a "Direct" line for debugging purposes. Entries in the Devices file take the following form:

ACU device-file null speed 212 x dialer
Direct device-file - Any direct

For example:

ACU ttyf2 null 38400 212 x usr
Direct ttyf2 - Any direct

ttyf2 specifies the device special file to use when dialing out.
The 38400 represents the speed of the connection. Note, this is the connection between the modem and the computer, not between modems. The modem should negotiate a speed with the modem it connects to.
The usr indicates the dialer from the /etc/uucp/Dialers file that will be used upon starting the connection.

Change the ownership of the device files so that the cu command may access them:

chown uucp /dev/tty[dmf]port-number

For example, for serial port 2:

chown uucp /dev/tty[dmf]2

The modem should now be ready to dial-out. Use the command:

cu -s speed -l device-file telephone-number

replacing speed with the configured speed, device-file with the appropriate device special file, and telephone-number with the phone number to be dialed.

Terms used: Hayes-compatible.