Cheney's original copying algorithm,from which all other copying alog-rithms are derived,divides memory into two spaces,and only uses one spsce at a time.It collects gsrbage by a breadth-first traversal of all nongarbage objects,copying them from from-space to to-dpace.Once all nongarbage objects have been copied,it reclaims all the memory in from-space by reversing the rolesing the roles of from-space and to-space.Real-time versions of this algorihm alwaays perform lazy copying