(setq skip 0)

(defun single-step (pc frame next env esc cont abs)
  (prog ()
     (block)
     (refresh-memory-gauges)
     (if (zerop (gettopval 'skip)) then
         (printout nil "Opcode is " (b-opcode (caar pc)) t)
         (break1 nil t))
     (settopval 'skip (imax 0 (sub1 (gettopval 'skip))))))