cty(4)
NAME
cty − extra serial line interface
DESCRIPTION
The extra serial lines are available to the processor through the console registers. These lines are available on the VAX 8100, 8200, 8300, 8500, 8550, 8600, 8650, 8700, and 8800 machines and number three all total. They act like normal terminal lines except for the VAX 8600 (8650) where the first line can also act as a remote console port and the other two lines are currently unused. Entries for these lines should be placed in /etc/ttys if they are used.
There are also certain workstation configurations that may use the console serial interface. For microvax workstation configurations, calling MAKEDEV() with the argument ttycp will create the device special file needed to utilize the console interface. Before using the serial line interface, it is important to consider the setting of the halt enable switch on a microvax workstation.
RESTRICTIONS
In general, the lines are low-performance devices. They can be used as terminal ports but for each character sent or received the CPU is interrupted. Thus it is recommended that the extra serial lines be used at low baud rates (2400 baud or less), so that console input and output will not severely impact system performance.
FILES
/dev/ttyc?