The pseudoterminal inherits its device characteristics from
the system default parameters, with the following exceptions:
The device inherits initial device
characteristics from the SYSGEN-supplied default values. You can modify
the device characteristics during device creation by supplying new
characteristics.
The HOSTSYNC terminal characteristic is always set.
The device is set to NOMODEM and cannot be set to
MODEM.
The device is set not to time output character transmission.
Hardware controllers time output character transmission to determine
whether the controller is broken.
You can obtain information on pseudoterminal characteristics
by using the Get Device/Volume Information ($GETDVI) system service,
as described in
Terminal Driver Device Information and
the HP OpenVMS System Services Reference Manual.
Applications should assign a channel other than the control
channel to read data from, write data to, read, or alter the pseudoterminal
characteristics. An attempt to perform such I/O with the control
channel, or any other attempt to queue an illegal or unsafe I/O
request, results in an SS$_CHANINTLK error.
HP OpenVMS I/O User's Reference Manual
Pseudoterminal Driver
