In the IBM world, the function keys are nicely standardized but there are also differences among the terminal types used. To connect to most IBM (and compatible but not AIX or AS/400) mainframes, you would use the Inet3270 terminal emulator. Here the telnet TN3270E setting (See the Setup | Telnet menu) can have a major influence on how well you communicate with the mainframe. By default Inet3270 will run with a terminal type of IBM-3270-5. A few other options listed in the drop down box under Setup | Telnet | Terminal Type, but you may also manually edit the strings as required. For proper TN3270E connections, the mainframe might require a –E in the terminal type as in IBM-3278-9-E.

The screen layout or color is wrong

IBM-3270 is a fairly generic name. IBM-3278 and IBM-3279 are also popular with the latter being a color terminal. The color instructions for an IBM-3278 and an IBM-3279 differ. The default configuration will use colors to distinguish text of various attributes even if the terminal is considered to be a monochrome terminal.

A mainframe will not send instructions to switch the terminal to 132-column mode, unless the terminal type contains a –5 as in IBM-3278-5. Your terminal will only go into 132-column mode if the proper command was sent from the server.

If you set a terminal type of IBM-3287, the mainframe will consider the terminal as a printer and may send print jobs to the terminal, which then acts as a print server.

The Inet5250 emulator is used mostly to connect to IBM AS/400 systems. The most popular and default terminal type is IBM-3179-2 with a few other options listed in the drop down box under Setup | Telnet | Terminal Type.

See also Configuring your 3287 printer.