Carl, thanks as always. That worked, of course. Another funny thing that happens when xy loads into Edward's emulation is that the disc-folder signifier prompt (ie., C:\XY4) at the top of xy's display blinks. Never did that before. I know there's a setting for that somewhere, but it's been many years . . .
Edward, thank you. Setting window width as you described (to 100) does not change the display from what I had when set at 80. Running 90X43 widens the display slightly, making the font slightly smaller, but does not change the screen real estate taken by the program by much. A more important issue for me is to create a 4dos shell other than the one packaged in, with my own initialization file, aliases, and so on; I can do this manually every time, but would like to have the program load that way at startup.
Again thanks to you both, especially Edward's non-support support!