5.45 How can I force Emacs to scroll only one line when I move past the bottom of the screen?

Customize the scroll-conservatively variable with M-x customize-variable <RET> scroll-conservatively <RET> and set it to a large value like, say, 10000. For an explanation of what this means, see Auto Scrolling.

Alternatively, use the following Lisp form in your .emacs:

     (setq scroll-conservatively most-positive-fixnum)