UNIX Serial Port Resources – Tutorials on Solaris/SunOS Modems and Terminals

This content was originally created, collected, and maintained by Stokely Consulting.
As of May 2005, it is being hosted and maintained by Bill Bradford.

Celeste Stokely’s Tutorial on Solaris 2.x Modems and Terminals
Tutorial which explains how to set up your Solaris 2.x serial ports for modems and/or terminals.
There is also a pure-ASCII version, 2xmodem.txt.

Celeste Stokely’s Tutorial on SunOS 4.1.x Modems and Terminals
Tutorial which explains how to set up your SunOS 4.1.3+ serial ports for modems and/or terminals.
There is also a pure-ASCII version, 4xmodem.txt.

How to disable BREAK on Sun serial ports:
A terminal connected to port A and acting as a Sun console can drop the Sun to the prom monitor prompt if you turn off or unplug the terminal. This Cisco field notice gives 3 solutions to disable BREAK on the serial port.


A Korn shell script that uses a question-and-answer format to make Solaris serial port setup easier than the pmadm and ttyadm commands. It’s not a GUI, so it will work when you’re logged in on a serial console port, or from a computer that doesn’t support X-Windows. Supports Solaris 2.6 and higher.

Winmodems are not modems

describes the differences between host-based, HCF-modems or HSP-modems which require software (drivers) in the OS to do the work of proper hardware modems. Winmodems don’t work with Unix, only Microsoft Windows. Great chart to see which modems are Winmodems, and which are real modems.

DTR Delay Problems:

By default, Suns have a three second delay in toggling dtr. If your Sun has a zs serial port you can set the variable default_dtrlow to control the number of seconds of the delay. If the variable is set to zero, dtr can be toggled many times a second. For example, in /etc/system add the line set zs:default_dtrlow = 1 to have a 1 second delay.
If your workstation has an se serial port, the /etc/system line should be set se:se_default_dtrlow = 1. However, in initial versions of the se driver, the delay was the value of (se_default_dtrlow + 1) seconds. If you have this version of the se driver, don’t set the value to -1 in /etc/system or the port will hang on open. If you need to toggle dtr quickly, you can still set the value to -1 after the terminal is opened by using adb to set the variable manually.
All this is Sun bugid 4230310, fixed by patch 105924-09 or higher. The patch makes se_default_dtrlow behave like default_dtrlow (i.e. setting
se_default_dtrlow to 0 will allow rapid toggling of dtr instead of once per second).

Attention Ultra-30 users:

For Solaris 2.6, you need Sun patch 105924. (So will Ultra-250 users.) For Solaris 2.5.1 you need Sun patch 104596. These patches solve many serial port related problems such as port monitors never releasing the port, always sending 1 stop bit, and general serial port hangs. These patches are available to Sun contract customers at http://sunsolve.sun.com.

Patch for increasing serial port speed on Solaris x86
Changes the Solaris x86 asy driver to allow speeds 57600bps and 115200bps by remapping speeds 50 and 75. Requires a 16550A or higher UART. Includes a special note for dp-4.0 users. This patch is not applicable to Solaris x86 2.5[.1] DU7 users. Written by Andrew Gabriel.

Configuring high-speed dialup on Solaris 7 and Solaris 8
A good admintool approach for setting up dialup and dialin. Part of the great Solaris Resources at Kempston.