The automatic terminal recognition software available through `native' MONGO in versions 6.1 and earlier has been withdrawn, to facilitate the switch to other graphics packages such as PGPLOT. For all packages, all terminal types are offered as explicit alternatives, and you must choose the correct one for SPECX to use the correct escape sequences for mode-toggling etc.
For correct use of the interactive graphics (using the graphics cursor or crosshair to read positions via the GIN, or Graphics INput, response), the terminal must be configured to produce exactly 6 GIN characters. That is, when you hit a key while the graphics crosshair is showing, the terminal should write only the 4 Tek4010/4014 location bytes, plus a byte corresponding to the key that was struck, and a further byte as terminator (carriage return is OK, ETX hangs PGPLOT). Use the terminal setup to ensure that these are not followed by spurious extra carriage returns, line feeds or EOTs.