A Write On Reference Mesh (WORM) detects a memory write operation to a reference location of a mesh entry in a memory window mesh and invokes an action responsive to the detected write. The mesh entries are laid out in zones. The invoked action is dependent on the individual mesh entry or the zone in which the write operation was detected. The action invoked can be configured by the custom logic provided by the vendor. Accordingly, in a special purpose processor, custom logic can trigger a wide variety of sophisticated actions by detecting a write operation to one of any number of specific memory addresses in the memory window.