The settings shown by SHOW TERMINAL indicate what OpenVMS believes to be the capabilities of the terminal. In other words, OpenVMS will behave as if the terminal possesses those, and only those, features. OpenVMS will send control codes (which control such things as line-and screen-editing functions) appropriate for such a terminal.
Should the default terminal settings be incorrect, you may adjust them via the SET TERMINAL command. The more common qualifiers are described below:
SET TERMINAL/INQUIRE—This command causes OpenVMS to query the terminal about its capabilities and adjust settings accordingly. Some terminals do not respond to this query and may cause a delay of several seconds while OpenVMS waits for an answer.
SET TERMINAL/DEVICE=VT100—Causes OpenVMS to adjust various settings as appropriate for a VT100 terminal. This command provides compatibility with a wide range of terminals and terminal emulators. Advanced functions will be achieved with combinations of simpler functions, which may slightly slow the terminal operation. Compare this with SET TERMINAL /DEVICE=VT200, VT300, VT400, etc., which cause OpenVMS to send advanced control functions, which simpler terminals cannot perform.
SET TERMINAL/DEVICE=UNKNOWN—If a device type of VT100 is unsuccessful, you may wish to try UNKNOWN, which causes OpenVMS to use very rudimentary settings and functions. Most users will never need to resort to this.
SET TERMINAL/INSERT—This sets INSERT mode. When editing a command, keystrokes will be inserted between existing characters.
SET TERMINAL/OVERSTRIKE—This sets OVERSTRIKE mode. When editing a command, keystrokes will overwrite existing characters. You may switch between INSERT and OVERSTRIKE modes at any time by pressing CTRL/A. This will take effect for the current command only, and will then be reset to its previous value.
SET TERMINAL/[NO]BROADCAST—Use NOBROADCAST to disable the reception of broadcast messages at your terminal. Use BROADCAST to enable their reception.
SET TERMINAL/PAGE and /WIDTH—For DECterm devices, use /PAGE to set the number of lines in the display (the default is 24). Use /WIDTH to set the number of columns (default values are 80 and 132). When changing these values, bear in mind that not all applications will perform correctly at settings other than the defaults /WIDTH=80 and /WIDTH=132 can be used with many terminals, but other values are less often supported.
The qualifiers described above are the most common. For information about other qualifiers, use HELP SET TERMINAL.