There is a hypertext version of the MACLISP manual provided by Kent Pitman at http://maclisp.info/
You can run MACLISP on modern computers by emulating a PDP-10 running ITS: http://klh10.trailing-edge.com/
MACLISP
MACLISP was the successor of LISP 1.5 at MIT and the predecessor of ZetaLisp.