This will garbage collect a few times. You can also give all of the hlife options, in which case hdraw will perform the computation just as hlife would before display. If the screen appears blank, hit - a few times to zoom out until some portion of the pattern appears. You can also click with the mouse to zoom in the area where you click. The format of the macrocell file is just a listing of the macrocell nodes, one node per line.
Every subsequent line is a node, starting with the node numbered one and proceeding sequentially.
If any node number is zero, this indicates that that child node is completely empty of any on-cells. The last node of the file is the root node.