VMS/IRAF Installation and Site Manager's Guide

6.1. Xterm

Xterm is a public-domain version of the standard MIT X window system terminal emulator, modified to work on VMS. It is a two-window tool capable of emulating a VT102 terminal and a Tektronix 4014 terminal. Appropriate escape sequences will cause xterm to switch between these two modes, but some programs require the user to make the change (using the CTRL-middle mouse button menu). It is especially valuable for IRAF use since it allows a plotted graph to be kept in the Tektronix emulation window while commands are given in the VT102 emulation window.

Due to significant changes between VMS and DECwindows versions, there are three different versions of xterm:

1) Xterm 1.1 (XTERM11.EXE) - for VMS 5.1 to 5.3-x, with DECwindows

2) Xterm 1.2 (XTERM12.EXE) - for VMS 5.4-x and later, with DECwindows

3) Xterm 2.1 (XTERM21.EXE) - for VMS 5.4-x and later, with DECwindows/Motif

A common mistake is to run the CL from a DECterm window, which does not support IRAF graphics. To use IRAF interactive graphics tasks one must run IRAF from an xterm window (or any similar terminal emulator supported by IRAF, e.g., gterm, xgterm, etc.). To use xterm with IRAF we recommend that the "xtermr" graphcap entry be used. This is set as follows:

cl> stty xtermr nl=54

By default, this entry has 65 lines in the text window. If your setup is different (perhaps 54 lines instead of 65) you can make changes as shown on the stty command line. The "xterm" stty setting is an alias for the "xtermr" stty setting; they can be used interchangeably.

The xtermr graphcap entry writes the status line in the TEK window, not in the text window. This is the preferred setup, since DEC hasn't yet made available the customize feature for "focus follows cursor", meaning there is no way around needing to click-to-focus. Use of xtermr requires the least amount of clicking.

You should not click inside the TEK window to focus on it, but on its header or border. Otherwise, the mouse click returns a character which terminates cursor mode. Clicking on the border provides focus without reporting any events, since the cursor is not inside the "active" region.