An integrated circuit includes memory units and at least one memory test module, each module includes one associated memory unit, a set of test registers therefor, and a test engine configured to perform a test operation on that associated memory unit. A transaction interface of the memory test module receives a transaction specifying a register access operation and providing a first address portion having encodings allowing individual memory units as well as groups of memory units to be identified, and a second address portion identifying one of the test registers within the set to be an accessed register. Decode circuitry, within each memory test module and responsive to the transaction, is configured to selectively perform the register access operation if it is determined that the memory test module includes a set of test registers associated with a memory unit.