Determine the height and width of the terminal, and store this information into variables for subsequent use.

(defun screen-dimensions ()
  (with-screen (scr :input-blocking t :input-echoing nil :cursor-visible nil)
    (let ((width (width scr))
          (height (height scr)))
      (format scr "The current terminal screen is ~A lines high, ~A columns wide.~%~%" height width)    
      (refresh scr)
      ;; wait for keypress
      (get-char scr))))