Additional Typeahead Considerations

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.