EDT Previous Screen
  Scrolls vertically to show the previous section of text---roughly 75% of
  the window size.
  Key:   The EDT keypad defines PREV SCREEN on the mini keypad.
  Usage notes:
  o  If the cursor is free (which is the default), it moves up in the same
     column on the screen regardless of whether text is there or not.
  o  If the cursor is bound, it moves up to the corresponding line
     positions, depending on the shape of your text, as in real EDT.
  o  For continuous movement, you can hold down or repeat PREV SCREEN until
     you reach the top of the buffer.
  Related topics:
     SET CURSOR BOUND    SET CURSOR FREE    TOP