There are a number of actions that should be avoided when
data is being typed ahead, such as changing a terminal's
speed or parity settings.
If you were to enter the speed command using typeahead, then
change the speed at the terminal and attempt to type ahead with
the new speed, the terminal would hang. Similarly, if you were to
change the parity setting before a typed ahead parity command could
execute, data would be lost. Either of these problems can be avoided
by simply not typing ahead when changing these settings. Wait for
the commands to execute before changing the terminal's
settings.
You will also encounter problems if you attempt to use typeahead
with VPLUS or user block mode. If your program allows block mode
reads, you should make sure that typeahead mode is disabled before
the terminal is placed in block mode. Because of the additional
terminal controls and status checks involved in processing a read
in block mode, it is not possible to use block mode and typeahead
at the same time.
Finally, no attempt should be made to enable typeahead from
a terminal connected via PAD. Typeahead mode is not supported for
this configuration.
