Echoplex mode is a mode in which characters you type are not displayed locally, but just sent to the host machine. Usually the host will send these back to you ('echo' them) as you type. If you are not seeing what you are typing then possibly you need to turn off echoplex mode (in which case Glink will display the characters locally). If you see every character you type twice, on the other hand, that's a fairly sure sign that echoplex mode needs to be turned on.