Three associative stores are interconnected to provide a data processor. A control store contains a microprogram and it emits tags that select a function table in a working store and data from a local store, the data being applied to the working store as a look-up argument. The local store may also hold a macroprogram. Two of the stores are interconnected so that a tag emitted by one is used to address the other and vice versa. A nonassociative main store may be connected to the local store.